#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

long long mod_inv(long long a, int m) {
  if ((a %= m) < 0) a += m;
  if (std::__gcd(a, static_cast<long long>(m)) != 1) return -1;
  long long b = m, x = 1, u = 0;
  while (b > 0) {
    long long q = a / b;
    std::swap(a -= q * b, b);
    std::swap(x -= q * u, u);
  }
  x %= m;
  return x < 0 ? x + m : x;
}

template <typename T>
std::pair<T, T> chinese_remainder_theorem(std::vector<T> b, std::vector<T> m) {
  T x = 0, md = 1;
  int n = b.size();
  for (int i = 0; i < n; ++i) {
    if ((b[i] %= m[i]) < 0) b[i] += m[i];
    if (md < m[i]) {
      std::swap(x, b[i]);
      std::swap(md, m[i]);
    }
    if (md % m[i] == 0) {
      if (x % m[i] != b[i]) return {0, 0};
      continue;
    }
    T g = std::__gcd(md, m[i]);
    if ((b[i] - x) % g != 0) return {0, 0};
    T ui = m[i] / g;
    x += (b[i] - x) / g % ui * mod_inv(md / g, ui) % ui * md;
    md *= ui;
    if (x < 0) x += md;
  }
  return {x, md};
}

int main() {
  constexpr int N = 3;
  std::vector<long long> x(N), y(N);
  for (int i = 0; i < N; ++i) std::cin >> x[i] >> y[i];
  long long ans, mod;
  std::tie(ans, mod) = chinese_remainder_theorem(x, y);
  if (mod == 0) {
    std::cout << "-1\n";
  } else {
    std::cout << (ans == 0 ? mod : ans) << '\n';
  }
  return 0;
}