diff --git a/thu_dsa/chp2/Fib.cpp b/thu_dsa/chp2/Fib.cpp
index 096f719..73fa75a 100644
--- a/thu_dsa/chp2/Fib.cpp
+++ b/thu_dsa/chp2/Fib.cpp
@@ -1,16 +1,13 @@
-#include "Fib.h"
-#include <iostream>
-using std::cout;
-using std::endl;
+#include "Vector.h"
 
 //constructor
 Fib::Fib(int n) {
-	elem = Vector<int>();
+	Vector<int>();
 	int prev = 0, current = 1, tmp;
 
-	elem.push_back(prev);
+	push_back(prev);
 	while (current < n) {
-		elem.push_back(current);
+		push_back(current);
 
 		tmp = prev;
 		prev = current;
@@ -20,14 +17,14 @@ Fib::Fib(int n) {
 
 //external interfaces
 void Fib::print() {
-	for (int ix = 0; ix != elem.getSize(); ++ix)
-		cout << elem[ix] << endl;
+	for (int ix = 0; ix != getSize(); ++ix)
+		cout << operator[](ix) << endl;
 }
 
 int Fib::get() {
-	return elem[elem.getSize() - 1];
+	return operator[](getSize() - 1);
 }
 
 void Fib::prev() {
-	elem.pop_back();
+	pop_back();
 }
diff --git a/thu_dsa/chp2/Fib.h b/thu_dsa/chp2/Fib.h
deleted file mode 100644
index ca3b372..0000000
--- a/thu_dsa/chp2/Fib.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef FIB_H_
-#define FIB_H_
-
-#include "Vector.h"
-
-class Fib{
-protected:
-	Vector<int> elem;
-public:
-	//constructor
-	Fib(int n);
-
-	void print();
-	int get();
-	void prev();
-};
-
-#endif
diff --git a/thu_dsa/chp2/Vector.h b/thu_dsa/chp2/Vector.h
index d6e017f..00b4f88 100644
--- a/thu_dsa/chp2/Vector.h
+++ b/thu_dsa/chp2/Vector.h
@@ -1,7 +1,6 @@
 #ifndef VECTOR_H_
 #define VECTOR_H_
 
-#include "Fib.h"
 #include <iostream>
 
 #define DEFAULT_CAPACITY 3
@@ -11,6 +10,10 @@
 using std::cout;
 using std::endl;
 
+template<typename T> 
+class Vector;
+class Fib;
+
 template<typename T>
 class Vector{
 protected:
@@ -322,4 +325,15 @@ void Vector<T>::mergeSort(int lo, int hi){
 	merge(lo, mid, hi);
 }
 
+
+class Fib : public Vector<int> {
+public:
+	//constructor
+	Fib(int n);
+
+	int  get();
+	void print();
+	void prev();
+};
+
 #endif
diff --git a/thu_dsa/chp2/testFib.cpp b/thu_dsa/chp2/testFib.cpp
index 9491bdb..b1ad021 100644
--- a/thu_dsa/chp2/testFib.cpp
+++ b/thu_dsa/chp2/testFib.cpp
@@ -1,4 +1,4 @@
-#include "Fib.h"
+#include "Vector.h"
 #include <cassert>
 #include <iostream>
 
diff --git a/thu_dsa/chp2/testVector.cpp b/thu_dsa/chp2/testVector.cpp
index fca246f..30d9e1d 100644
--- a/thu_dsa/chp2/testVector.cpp
+++ b/thu_dsa/chp2/testVector.cpp
@@ -1,4 +1,3 @@
-#include "Fib.h"
 #include "Vector.h"
 #include <time.h>
 #include <cassert>