#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <limits.h>
#include <time.h>
#include <string>
#include <string.h>
#include <sstream>
#include <set>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <stack>
#include <queue>

using namespace std;

typedef long long ll;

ll gcd(ll a, ll b){
  if(b == 0) return a;
  return gcd(b, a%b);
}

ll lcm(ll a, ll b){
  return a*b / gcd(a, b);
}

int main(){
  ll x1, y1, x2, y2, x3, y3;
  cin >> x1 >> y1;
  cin >> x2 >> y2;
  cin >> x3 >> y3;
  ll n1, n2;
  bool success = false;
  ll l = lcm(y1, y2);

  for(int i = 0; i <= y2 && !success; i++){
    n1 = x1 + y1 * i;

    if (n1 > 0 && n1 % y2 == x2) {
      for(int j = 0; j <= y3 && !success; j++){
        n2 = n1 + l * j;

        if (n2 % y3 == x3) {
          success = true;
          break;
        }
      }
    }
  }

  if (success) {
    cout << n2 << endl;
  } else {
    cout << -1 << endl;
  }

  return 0;
}