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

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
    int a,b,c;
    cin >> a >> b >> c;
    bool f = false;
    for(int i = 1; i <= 100000; i++) {
        long long now = 1ll*i*a;
        if(now > b) now -= b;
        if(now == c) {
            cout << i << endl;
            f = true;
        }
    }
    if(!f) cout << -1 << endl;
}