#include <bits/stdc++.h>
using namespace std;
int main() {
    int x = 15;
    vector<int> path; // 动态数组
    while (x) {
        int a = x % 2;
        path.push_back(a);
        x /= 2;
    }
    for (int i = path.size() - 1; i >= 0; i--)
        cout << path[i];
    return 0;
}