#include <bits/stdc++.h>
using namespace std;
#define bokusunny ios::sync_with_stdio(false), cin.tie(nullptr);

#include <atcoder/math>
using namespace atcoder;

void solve() {
  vector<long long> R(3), M(3);
  for (int i = 0; i < 3; i++) {
    cin >> R[i] >> M[i];
  }

  auto p = crt(R, M);
  if (p == make_pair(0LL, 0LL)) {
    cout << -1 << endl;
  } else if (p.first == 0) {
    cout << p.second << endl;
  } else {
    cout << p.first << endl;
  }
}

int main() {
  bokusunny;
  solve();

  return 0;
}