#include<iostream>
#include<vector>
using namespace std;
int main()
{
    vector<int> v ={56,78,34,45};
    cout<<"initial vector:"<<"\n";
    for(int i:v)
    cout<<i<<"\n";
v.push_back(100);
v.push_back(200);
cout<<"after adding two element,contents of vector are:\n";
  for(int i:v)
  cout<<i<<"\n";
cout<<"element at index 1:"<<v.at(1)<<"\n";
cout<<"element at index 3:"<<v.at(3)<<"\n";
v.at(4)=700;
cout<<"after updating,the contents of vector:\n";
for(int i:v)
   cout<<i<<"\n";
   
v.pop_back();
v.pop_back();
cout<<"after deleting an element,contens of vector are:\n";
for(int i:v)
  cout<<i<<"\n";
  return 0;
}