#include <bits/stdc++.h>
using namespace std;

void solve() {
    int a, b, c;
    cin >> a >> b >> c;
    bool flag = true;
    for (long long n = 1; n <= 200000; n++) {
        long long v = a * n;
        if (v > b) {
            v -= b;
        }
        if (v == c) {
            cout << n << '\n';
            flag = false;
        }
    }

    if (flag) {
        cout << -1 << '\n';
    }
}

int main() {
    int q = 1;
    // cin >> q;
    while (q--) {
        solve();
    }
}