#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
ll mod=1e9+7;
#define rep(i,a) for (int i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}

//a*x+b*y=gcd(a,b)となるx,yにする　返り値gcd(a,b)
ll Euclid(ll a,ll b,ll &x,ll &y){
    if(b==0){
        x=1,y=0;
        return a;
    }
    ll d=Euclid(b,a%b,y,x);
    y-=a/b*x;
    return d;
}

// val1=(a,p) val2=(b,q)
// return (c,r)
// c: c%p==a && c%q==b
// r: r=lcm(a,b)
// need: a%gcd(p,q)==b%gcd(p,q)
// use: Euclid
std::pair<long long,long long> ctr_sub(std::pair<long long,long long> val1,std::pair<long long,long long> val2){
	long long a,b,p,q;
	long long X,Y,G,ans_val,ans_mod;
	tie(a,p)=val1;
	tie(b,q)=val2;
	if(a==-1||b==-1) return {-1,-1};
	G=Euclid(p,q,X,Y);
	if((b-a)%G!=0) return {-1,-1};
	ans_mod=p*(q/G);
	ans_val=(p*((X*((b-a)/G))%q))%ans_mod+a;
	return {(ans_val%ans_mod+ans_mod)%ans_mod,ans_mod};
}

//  rainy ~ 雨に打たれて ~
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n=3;
	pair<ll,ll> ans={0,1};
	rep(i,n){
		ll x,y;
		cin>>x>>y;
		ans=ctr_sub(ans,{x,y});
	}
	cout<<ans.first<<"\n";
}