diff --git a/multilevelinheritance.cpp b/multilevelinheritance.cpp
new file mode 100644
index 0000000..6699323
--- /dev/null
+++ b/multilevelinheritance.cpp
@@ -0,0 +1,36 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+class Triangle{
+	public:
+		void triangle(){
+			cout<<"I am a triangle\n";
+		}
+};
+
+class Isosceles : public Triangle{
+  	public:
+  		void isosceles(){
+    		cout<<"I am an isosceles triangle\n";
+  		}
+};
+
+//Write your code here.
+class Equilateral : public Isosceles{
+      public:
+          void equilateral(){
+            cout<<"I am an equilateral triangle\n";
+          }
+};
+int main(){
+  
+    Equilateral eqr;
+    eqr.equilateral();
+    eqr.isosceles();
+    eqr.triangle();
+    return 0;
+}
diff --git a/pointer.cpp b/pointer.cpp
new file mode 100644
index 0000000..a80a976
--- /dev/null
+++ b/pointer.cpp
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+void update(int *a,int *b) {
+    int p,q;
+    p = *a+*b;
+    q = *a-*b;
+    if(q<0){
+        q*=-1;
+    } 
+    *a=p;
+    *b=q;
+}
+
+int main() {
+    int a, b;
+    int *pa = &a, *pb = &b;
+    
+    scanf("%d %d", &a, &b);
+    update(pa, pb);
+    printf("%d\n%d", a, b);
+
+    return 0;
+}
diff --git a/sets.cpp b/sets.cpp
new file mode 100644
index 0000000..5e677f7
--- /dev/null
+++ b/sets.cpp
@@ -0,0 +1,37 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <set>
+#include <algorithm>
+using namespace std;
+
+
+int main() {
+    set<int> s;
+    int i, n, q, a, b;
+    set<int>::iterator j;
+    cin>>q;
+    for(i=0;i<q;i++){
+        cin>>a>>b;
+        if(a==1){
+            s.insert(b);
+        }
+        else if(a==2){
+            s.erase(b);
+        }
+        else{
+            j = s.find(b);
+            if(j==s.end()){
+                cout<<"No"<<endl;
+            }
+            else {
+            cout<<"Yes"<<endl;
+            }
+        }
+    }
+    return 0;
+}
+
+
+
diff --git a/variablesizedarray.cpp b/variablesizedarray.cpp
new file mode 100644
index 0000000..fd0ba19
--- /dev/null
+++ b/variablesizedarray.cpp
@@ -0,0 +1,30 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+
+int main() {
+    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
+    int n;
+    int q;
+    cin >> n >> q;
+    vector<int> a[n];
+    for(int i = 0; i < n; i++){
+        int m;
+        cin >> m;
+        int o;
+        for(int j = 0; j < m; j++){
+            cin >> o;
+            a[i].push_back(o);
+        }
+    }
+    int r, s;
+    for(int k = 1; k <= q; k++){
+        cin >> r >> s;
+        cout << a[r][s] << endl;
+    }
+    return 0;
+}