#include <bits/stdc++.h>
#define rep(i, a, n) for(ll i = a; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1001001001;
const ll LINF = 1001002003004005006ll;
//const int mod = 1000000007;
//const int mod = 998244353;

int main()
{
  ll a, b, c;
  cin >> a >> b >> c;
  int flag = 0;
  rep(i, 1, 1e6) {
    if (a*i - b > 0 && a*i - b == c) {
      cout << i << endl;
      flag = 1;
    }
    else if (a*i - b <= 0 && a*i == c) {
      cout << i << endl;
      flag = 1;
    }
  }
  if (!flag) cout << -1 << endl;
  return 0;
}