#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;
typedef long long ll;

ll gcd(ll a, ll b) {
	return b != 0 ? gcd(b, a % b) : a;
}
ll lcm(ll a, ll b) {
	return a * b / gcd(a, b);
}
//ax + by = gcd(a,b);
ll extgcd(ll a,ll b,ll &x,ll &y) {
	ll g = a; x = 1; y = 0;
	if (b != 0)g = extgcd(b, a%b, y, x), y -= (a / b)*x;
	return g;
}

int main()
{
	bool flag = true;
	ll x1, x2, x3, y1, y2, y3; cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
	ll s1 = x2 - x1;
	ll a, b, g1; g1 = extgcd(y1,y2,a,b);
	if (s1%g1)flag = false;
	a *= s1/g1; b *= -s1/g1;
	a += y2, b += y1;
	ll x4 = y1*a + x1;
	ll y4 = lcm(y1,y2);
	ll s2 = x3 - x4;
	ll c, d, g2; g2 = extgcd(y4, y3, c, d);
	if (s2%g2)flag = false;
	c *= s2/g2; d *= -s2/g2;
	c += y3, d += y4;
	ll x5 = y3*d + x3;
	if (flag) {
		cout << x5 << endl;
	}
	else cout << -1 << endl;
    return 0;
}