#include <bits/stdc++.h>
#include<boost/multiprecision/cpp_int.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

using lll=boost::multiprecision::cpp_int;
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

template <typename T>
T mypow(T x, T n, const T &p = -1)
{ //x^nをmodで割った余り
	T ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;

template<typename T=ll>
T extgcd(T a,T b,T &x,T &y){
	T d=a;
	if(b!=0){
		T res=a%b;
		d=extgcd(b,res,y,x);
		y-=(a/b)*x;
	}
	else{
		x=1;y=0;
	}
	return d;
}

template<typename T>
pair<T,T> crt(const vector<T> &r,const vector<T> &m){
	T R=0,M=1;
	assert(r.size()==m.size());
	for(int i=0;i<m.size();++i){
		T a,b;
		T d=extgcd<T>(M,m[i],a,b);
		
		if((r[i]-R)%d!=0)return{-1,-1};

		R+=M*(r[i]-R)/d*a;
		M*=m[i]/d;
	}
	pair<T,T>ans={(M+R%M)%M,M};
	return ans;
}

void solve()
{
	vector<ll>x(3),y(3);
	rep(i,3)cin>>x[i]>>y[i];
	auto p=crt<ll>(x,y);
	if(p.first==-1&&p.second==-1){
		cout<<-1<<"\n";
	}else{
		cout<<p.first<<"\n";
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}