#include <bits/stdc++.h>
#include <atcoder/all>
#define M_PI       3.14159265358979323846   // pi

using namespace std;
using namespace chrono;
using namespace atcoder;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;
typedef tuple<ll, ll, ll, ll, ll, ll> t6;
typedef tuple<ll, ll, string> tts;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define rrep(a,n) for(int a = n-1;a >= 0;a--)
#define repi(a,b,n) for(int a = b;a < n;a++)

template<typename T>
void chmax(T& a, T v) {
	a = max(a, v);
}

template<typename T, typename TVal>
void chcmpmax(map<T, TVal>& a, T key, TVal value) {
	if (a.count(key)) {
		chmax(a[key], value);
	}
	else {
		a[key] = value;
	}
}

template<typename T, typename TVal>
void chcmpmax(unordered_map<T, TVal>& a, T key, TVal value) {
	auto it = a.find(key);
	if (it == a.end())
	{
		a[key] = value;
	}
	else
	{
		if (it->second < value)
		{
			it->second = value;
		}
	}
}


template<typename T>
void chmin(T& a, T v) {
	a = min(a, v);
}

template<typename T, typename TVal>
void chcmpmin(map<T, TVal>& a, T key, TVal value) {
	if (a.count(key)) {
		chmin(a[key], value);
	}
	else {
		a[key] = value;
	}
}

int main() {
	vector<ll> xs(3), ys(3);
	rep(i, 3)
	{
		cin >> xs[i] >> ys[i];
	}
	auto ans = atcoder::crt(xs, ys);
	if (ans == P{0,0})
	{
		cout << -1 << endl;
	}
	else
	{
		if (ans.first == 0)
		{
			cout << ans.second << endl;
		}
		else
		{
			cout << ans.first << endl;
		}
	}
	return 0;
}