#include <iostream>
using namespace std;

int main() {
    int A, B, C;
    cin >> A >> B >> C;

    bool flag = false;
    for (int N = 1; N <= C; N++) {
        if (N*A - B == C) {
            cout << N << endl;
            flag = true;
        }
    }

    if (!flag) {
        cout << -1 << endl;
    }

    return 0;
}