#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <iomanip>
#include <assert.h>
#include <array>
#include <cstdio>
#include <cstring>
#include <random>
#include <functional>
#include <numeric>
#include <bitset>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(c) (c).begin(), (c).end()
#define zero(a) memset(a, 0, sizeof a)
#define minus(a) memset(a, -1, sizeof a)
#define minimize(a, x) a = std::min(a, x)
#define maximize(a, x) a = std::max(a, x)

typedef unsigned long long ll;
int const inf = 1<<29;

int main() {

  int xs[3], ys[3];
  rep(i, 3) {
    cin >> xs[i] >> ys[i];
  }

  set<ll> s;
  ll curr = xs[0];
  rep(i, 1e8) {
    s.insert(curr);
    curr += ys[0];
    if(curr >= std::numeric_limits<ll>::max() - ys[0]) { break; }
  }

  set<ll> t;
  for(auto& e: s) {
    if(e % ys[1] == xs[1]) {
      t.insert(e);
    }
  }

  curr = xs[2];
  for(auto& e: t) {
    if(e % ys[2] == xs[2]) {
      cout << e << endl;
      exit(0);
    }
  }

  cout << -1 << endl;

  return 0;
}