#include <iostream>
#include <vector>

int main(void){
    std::vector<int> v(3);

    v[0] = 10;
    v[1] = 20;
    v[2] = 30;

    std::vector<int>::iterator it = v.begin();
    v.insert(it + 3, 40);

    for(int i=0; i < (int)v.size(); i++){
        std::cout << v[i] << std::endl;
    }

    return 0;
}