#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;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const 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() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

template <typename T>
pair<T, T> ext_gcd(T a, T b) {
  if (b == 0) return {1, 0};
  T fst, snd; tie(fst, snd) = ext_gcd(b, a % b);
  return {snd, fst - a / b * snd};
}

template <typename T>
pair<T, T> crt(const vector<T> &b, const vector<T> &m) {
  T x = 0, md = 1;
  int n = b.size();
  REP(i, n) {
    T g = __gcd(md, m[i]);
    if ((b[i] - x) % g != 0) return {0, -1};
    x += md * ((b[i] - x) / g * ext_gcd(md, m[i]).first % (m[i] / g));
    md *= m[i] / g;
  }
  return {x < 0 ? x + md : x, md};
}

int main() {
  const int N = 3;
  vector<ll> x(N), y(N); REP(i, N) cin >> x[i] >> y[i];
  pair<ll, ll> ans = crt(x, y);
  cout << (ans.second == -1 ? -1 : ans.first) << '\n';
  return 0;
}