#include <iostream>
#include <deque>
using namespace std;

int main() {

    deque<int> dq;

    dq.push_back(1);
    dq.push_back(2);
    dq.push_back(3);

    dq[0] = 10;

    for(int i = 0; i < dq.size(); i++){
        cout << dq[i] << " " ;
    }
    return 0;
}