#include <iostream>
#include <vector>
using namespace std;
int main() {
    vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);
    v.pop_back();
    v.insert(v.begin() + 1, 4);
    cout << v[2] << endl;
    return 0;
}