#include "bits/stdc++.h"
using namespace std;

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

int main() {
	long long X1, Y1, X2, Y2, X3, Y3;
	cin >> Y1 >> X1 >> Y2 >> X2 >> Y3 >> X3;
	long long ans = Y3;
	if (Y3 == 0) ans = X3;
	int count = X2 + 1000;

	long long add = X3;

	while (count > 0 && ans >= 0){
		if (ans % X2 == Y2) break;
		ans += add;
		count--;
	}
	if (count <= 0 || ans < 0){
		cout << -1 << endl;
		return 0;
	}

	add = (X3 * X2) / gcd(X3, X2);

	count = X1 + 1000;
	while (count > 0){
		if (ans % X1 == Y1) break;
		ans += add;
		count--;
	}

	if (count <= 0 || ans < 0){
		cout << -1 << endl;
		return 0;
	}

	cout << ans << endl;
}