#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;

    while (Q--) {

        ll a, b, c;
        cin >> a >> b >> c;
        bool f = 0;
        for (ll i = 1; i <= 1e6; i++) {
            ll x = i * a;
            if (x > b)x -= b;
            if (x == c) {
                f = 1;
                cout << i << endl;
            }
        }
        if (!f)cout << -1;
        

    }

    return 0;
}