#include <iostream>
using namespace std;
int main() {
    int x = 0, y = 0, z = 0;

    cout << "X: ";
    cin >> x;

    cout << "Y: ";
    cin >> y;

    cout << "Z: ";
    cin >> z;

    x = (x == 0 && (y >= 0 && z >= 0)) ? x = y+z: x = x;
    cout << x;
    return 0;
}