#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
int main() {
    // Input
    int A, B, C;
    cin >> A >> B >> C;

    // Output
    int cnt = 0;
    if (C % A == 0) cout << C / A << endl, ++cnt;
    if ((B + C) % A == 0) cout << (B + C) / A << endl, ++cnt;
    if (!cnt) cout << -1 << endl;
}