#include <bits/stdc++.h>

using namespace std;

template <typename T>
std::tuple<T, T, T> egcd(T a, T b) {
  T x = 1, y = 0, u = 0, v = 1;
  while (b != 0) {
    T t = a / b;
    a -= t * b;
    x -= t * u;
    y -= t * v;
    std::swap(a, b);
    std::swap(x, u);
    std::swap(y, v);
  }
  return {a, x, y};
}

template <typename T>
std::optional<std::pair<T, T>> crt(const std::vector<T> &r, const std::vector<T> &m) {
  assert(r.size() == m.size());
  T x = 0, y = 1;
  for (std::size_t i = 0; i < r.size(); i++) {
    T u = r[i], v = m[i];
    if (y < v) {
      std::swap(x, u);
      std::swap(y, v);
    }
    auto [d, a, _] = egcd(y, v);
    if ((u - x) % d != 0) return std::nullopt;
    T t = v / d;
    x += (u - x) / d % t * a % t * y;
    y *= t;
  }
  if (x < 0) x += y;
  return std::make_pair(x, y);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  vector<int64_t> X(3), Y(3);
  for (int i = 0; i < 3; i++) {
    cin >> X[i] >> Y[i];
  }
  auto res = crt(X, Y);
  if (res) {
    if (res.value().first == 0) {
      cout << res.value().second << '\n';
    } else {
      cout << res.value().first << '\n';
    }
  } else {
    cout << -1 << '\n';
  }
  return 0;
}