diff --git a/Makefile b/Makefile
index f12ba0c..c53e19a 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CC = g++
 all: sim
 
 sim: main.cpp block.cpp set.cpp simulator.cpp
-	$(CC) main.cpp block.cpp set.cpp simulator.cpp -o sim
+	$(CC) -std=c++11 main.cpp block.cpp set.cpp simulator.cpp -o sim
 
 clean:
 	rm sim
diff --git a/main.cpp b/main.cpp
index 9a72087..e373753 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,9 +1,10 @@
 #include <iostream>
 #include <math.h>
+#include <string.h>
 #include <iomanip>
 #include "simulator.h"
 
-int main(){
+int main(int argc, char* argv[]){
 	std::string temp;
 	int machineBits, cacheSize, waySize, blockSize;
 	short setSize;
@@ -23,62 +24,71 @@ int main(){
 	std::cout << "num_set: " << setSize << std::endl;
 	std::cout << "num_block_offset_bit: " << offsetSize << std::endl;
 	std::cout << "num_index_bit: " << indexSize << std::endl;
-	std::cout << "num_tag_bit: " << tagSize << std::endl << std::endl;
+	std::cout << "num_tag_bit: " << tagSize << std::endl;
 	
-	CacheSim::Simulator FIFOSim(machineBits, setSize, waySize, tagSize, 0);
-	CacheSim::Simulator LRUSim(machineBits, setSize, waySize, tagSize, 1);
+	CacheSim::Simulator* Sim;
+	if(strcmp(argv[1], "FIFO") == 0){
+		Sim = new CacheSim::Simulator(machineBits, setSize, waySize, tagSize, 0);
+	}else if(strcmp(argv[1], "LRU") == 0){
+		Sim = new CacheSim::Simulator(machineBits, setSize, waySize, tagSize, 1);
+	}else{
+		std::cout << "Usage: ./sim [ LRU | FIFO]" << std::endl;
+		return 0;
+	}
 
 	std::string action, address;
 	bool status;
-	std::vector<std::pair<std::string, bool>> LRUResult, FIFOResult;
+	std::vector<std::tuple<std::string, std::string, bool, short, short>> Result;
 	while(std::cin >> action >> address){
 		// std::cout << "action: "<< action << " address: " << address << std::endl; 
-		status = FIFOSim.read(address);
-		FIFOResult.push_back(std::make_pair(address, status));
-
-		status = LRUSim.read(address);
-		LRUResult.push_back(std::make_pair(address, status));
+		tuple<bool, short, short> status = Sim->read(address);
+		Result.push_back(
+			std::make_tuple(
+				action,
+				address,
+				std::get<0>(status),
+				std::get<1>(status),
+				std::get<2>(status)
+			)
+		);
 		// std::cout << std::endl << std::endl;
 	}
 	// FIFO
 
 	int allCount = 0, hitCount = 0;
-	
-	std::cout << "FIFO Replace Policy:" << std::endl;
-	for(int i=0; i<FIFOResult.size(); i++){
-		std::cout << "    " << std::setw(6) << std::setfill('0') << FIFOResult[i].first << "... ";
+	// std::cout << argv[1] << " Replace Policy:" << std::endl;
+	for(int i=0; i<Result.size(); i++){
+		// std::cout << "    " << std::setw(6) << std::setfill('0') << Result[i].first << "... ";
 		allCount++;
-		if(FIFOResult[i].second){
+		if(std::get<2>(Result[i])){
 			hitCount++;
-			std::cout << "HIT" << std::endl;
-		}else{
-			std::cout << "MISS" << std::endl;
 		}
 	}
-	std::cout << std::endl;
-	std::cout << "    Hit rate: " << (double)hitCount/allCount*100 << "%" << std::endl;
-	std::cout << "    Miss rate: " << 100 - (double)hitCount/allCount*100 << "%" << std::endl << std::endl;
+	std::cout << "num_total_access: " << allCount << std::endl;
+	std::cout << "num_hit: " << hitCount << std::endl;
+	std::cout << "num_miss: " << allCount - hitCount << std::endl;
+	std::cout << "hit_rate: " << std::fixed << std::setprecision(2) << (double)hitCount/allCount*100 << "%" << std::endl;
+	std::cout << std::endl << "hit trace:" << std::endl << std::endl;
 
+	for(int i=0; i<Result.size(); i++){
+		if(std::get<2>(Result[i])){
+			std::cout << std::get<0>(Result[i]) << " " << std::get<1>(Result[i]);
+			std::cout << " hit ";
 
+			std::cout << "set: ";
+			if(std::get<3>(Result[i]) != 0)
+				std::cout << "0x" << std::hex << std::get<3>(Result[i]) << " ";
+			else
+				std::cout << "0 ";
 
-	// LRU
-
-	allCount = 0, hitCount = 0;
-	std::cout << "LRU Replace Policy:" << std::endl;
-	for(int i=0; i<LRUResult.size(); i++){
-		std::cout << "    " << LRUResult[i].first << "... ";
-		allCount++;
-		if(LRUResult[i].second){
-			hitCount++;
-			std::cout << "HIT" << std::endl;
-		}else{
-			std::cout << "MISS" << std::endl;
+			std::cout << "way: ";
+			if(std::get<4>(Result[i]) != 0)
+				std::cout << "0x" << std::hex << std::get<4>(Result[i]);
+			else
+				std::cout << "0";
+			
+			if(i != Result.size()-1)
+				std::cout << std::endl;
 		}
 	}
-
-	std::cout << "num_total_access: " << setSize << std::endl;
-
-	std::cout << std::endl;
-	std::cout << "    Hit rate: " << (double)hitCount/allCount*100 << "%" << std::endl;
-	std::cout << "    Miss rate: " << 100 - (double)hitCount/allCount*100 << "%" << std::endl;
 }
diff --git a/set.cpp b/set.cpp
index 3cb9aaa..146ac8a 100644
--- a/set.cpp
+++ b/set.cpp
@@ -18,7 +18,7 @@ Set::Set(short waySize, short tagSize, short replacePolicy){
     }
 }
 
-bool Set::read(vector<bool> tag, short offset){
+tuple<bool, short> Set::read(vector<bool> tag, short offset){
     // HIT 的情況
     short baseAccessTime;       // 被替換掉的 block ，它的 access time
     for(int i=0; i<this->waySize; i++){
@@ -29,17 +29,19 @@ bool Set::read(vector<bool> tag, short offset){
                 this->countAccess(baseAccessTime);        // 更新計算所有 way access 的時間點
                 // cout << "HIT: 在 " << i << " way 找到！" << endl;
             }
-            return true;
+            return std::make_tuple(true, i);
         }
     }
 
     // MISS 的情況，需要寫入 $
+    short writeWay;
     if(this->emptySize > 0){
         for(int i=0; i<this->waySize; i++){
             if(this->blocks[i].getValid() == false){
                 // cout << "MISS: 在 " << i <<" way 寫入資料" << endl;
                 this->blocks[i].update(tag);    // 更新 tag
                 this->blocks[i].access();
+                writeWay = i;
                 baseAccessTime = this->waySize; // 每個都要更新
                 break;
             }
@@ -63,6 +65,7 @@ bool Set::read(vector<bool> tag, short offset){
         baseAccessTime = this->blocks[maxIndex].getAccessTime();
         this->blocks[maxIndex].update(tag);
         this->blocks[maxIndex].access();
+        writeWay = maxIndex;
 
         // for(int i=0; i<this->waySize; i++){
         //     vector<bool> t = this->blocks[i].getTag();
@@ -74,7 +77,7 @@ bool Set::read(vector<bool> tag, short offset){
     }
     
     this->countAccess(baseAccessTime);
-    return false;
+    return std::make_tuple(false, writeWay);
 }
 
 void Set::countAccess(short baseAccessTime){
diff --git a/set.h b/set.h
index 0a7e6a3..0fd6b60 100644
--- a/set.h
+++ b/set.h
@@ -1,7 +1,9 @@
 #include "block.h"
 #include <vector>
+#include <tuple>
 
 using std::vector;
+using std::tuple;
 using CacheSim::Block;
 
 namespace CacheSim{
@@ -15,7 +17,7 @@ namespace CacheSim{
 
     public:
         Set(short waySize, short tagSize, short replacePolicy);
-        bool read(vector<bool> tag, short offset);
+        tuple<bool, short> read(vector<bool> tag, short offset);
         void countAccess(short baseAccessTime);
 
     };
diff --git a/simulator.cpp b/simulator.cpp
index a21f662..063a3cc 100644
--- a/simulator.cpp
+++ b/simulator.cpp
@@ -15,7 +15,7 @@ Simulator::Simulator(int machineBits, short setSize, short waySize, short tagSiz
     }
 }
 
-bool Simulator::read(string address){
+tuple<bool, short, short> Simulator::read(string address){
     vector<bool> addrBits = this->addressTranslate(address);
     // for(int i=0; i<addrBits.size(); i++){
         // std::cout << addrBits[i] << " ";
@@ -25,11 +25,13 @@ bool Simulator::read(string address){
     short offset = this->getValue(addrBits, "offset");
     vector<bool> tag(addrBits.begin(), addrBits.begin()+this->tagSize);
     // std::cout<<"更新 index: "<<index<<std::endl;
-    return this->sets[index].read(tag, offset);
-}
 
-bool Simulator::write(string address){
-    return true;
+    tuple<bool, short> setResult = this->sets[index].read(tag, offset);
+    return std::make_tuple(
+        std::get<0>(setResult),
+        index,
+        std::get<1>(setResult)
+    );
 }
 
 vector<bool> Simulator::addressTranslate(string address){
diff --git a/simulator.h b/simulator.h
index 4889216..3f52618 100644
--- a/simulator.h
+++ b/simulator.h
@@ -1,9 +1,11 @@
 #include "set.h"
 #include <vector>
+#include <tuple>
 #include <iostream>
 #include <math.h>
 using CacheSim::Set;
 using std::vector;
+using std::tuple;
 using std::string;
 
 namespace CacheSim{
@@ -17,8 +19,7 @@ namespace CacheSim{
             vector<Set> sets;
         public:
             Simulator(int machineBits, short setSize, short waySize, short tagSize, short replacePolicy);
-            bool read(string address);
-            bool write(string address);
+            tuple<bool, short, short> read(string address);
             vector<bool> addressTranslate(string address);
             short getValue(vector<bool> addrBits, string type);
     };