#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

typedef pair<long long, long long> PLL;

template <class T>
T gcd(T a, T b) {
	return b == 0 ? a : gcd(b, a % b);
}

template <class T>
T lcm(T a, T b) {
	return a / gcd(a, b) * b;
}


int main() {
	long long x1, y1, x2, y2, x3, y3;
	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;

	PLL big, small;
	long long lcm12 = lcm(y1, y2);
	if (y1 > y2) {
		big   = make_pair(x1, y1);
		small = make_pair(x2, y2);
	} else {
		big   = make_pair(x2, y2);
		small = make_pair(x1, y1);
	}

	long long y12 = lcm12;
	long long x12 = -1;
	for (long long i = big.first; i < lcm12; i += big.second) {
		if (i % small.second == small.first) {
			x12 = i;
			break;
		}
	}

	if (x12 == -1) {
		cout << -1 << endl;
		return 0;
	}

	long long lcm123 = lcm(y12, y3);
	if (y12 > y3) {
		big   = make_pair(x12, y12);
		small = make_pair(x3,  y3);
	} else {
		big   = make_pair(x3,  y3);
		small = make_pair(x12, y12);
	}

	long long x123 = -1;
	for (long long i = big.first; i < lcm123; i += big.second) {
		if (i % small.second == small.first) {
			x123 = i;
			break;
		}
	}

	cout << x123 << endl;
	return 0;
}