#include <iostream>
#include <vector>
#include <algorithm>
//(val, lcm(m1, m2)): val=b1(mod m1), val=b2(mod m2)
std::pair<long long, long long> crt(long long b1, long long m1, long long b2, long long m2)
{
    long long x = 1, y = 0, x1 = 0, y1 = 1, g = m1, b = m2;
    while (b != 0)
    {
        long long n = g / b;
        g %= b; std::swap(g, b);
        x -= x1 * n; std::swap(x, x1);
        y -= y1 * n; std::swap(y, y1);
    }
    if ((b2 - b1) % g != 0) return {0, -1};
    long long lc = m1 / g * m2;
    return {((b1 + m1 * ((b2 - b1) / g * x % (m2 / g))) % lc + lc) % lc, lc};
}
using namespace std;

int main()
{
	int x[3], y[3];
	for (int i = 0; i < 3; ++i) cin >> x[i] >> y[i];
	pair<long long, long long> ans = crt(x[0], y[0], x[1], y[1]);
	if (ans.second == -1)
	{
		cout << -1 << endl;
		return 0;
	}
	ans = crt(ans.first, ans.second, x[2], y[2]);
	if (ans.second == -1) cout << -1 << endl;
	else cout << ans.first << endl;
}