#include <bits/stdc++.h>

 
 
typedef long long ll;
 
using namespace std;

#define rep(i,n)  for(int i=0;i<(n);i++)
const ll INF=1000000000000000000;

ll mod(ll a,ll m){
    return (a%m+m)%m;
}

ll extGcd(ll a,ll b,ll &p,ll &q){
    if(b==0){
        p=1;
        q=0;
        return a;
    }
    ll d=extGcd(b,a%b,q,p);
    q-=a/b*p;
    return d;
}

pair<ll,ll> ChineseRem(const vector<ll> &b,const vector<ll> &m){
    ll r=0,M=1;
    for(int i=0;i<(int)b.size();++i){
        ll p,q;
        ll d=extGcd(M,m[i],p,q);
        if((b[i]-r)%d!=0)return make_pair(0,-1);
        ll tmp=(b[i]-r)/d*p%(m[i]/d);
        r+=M*tmp;
        M*=m[i]/d;
    }
    return make_pair(mod(r,M),M);
}

int main(){
    
    vector<ll> x(3);
    vector<ll> y(3);
    for(int i=0;i<3;i++){
        cin>>x[i];
        cin>>y[i];
    }
    
    pair<ll,ll> p=ChineseRem(x,y);
    
    if(p.second==-1){cout<<-1<<endl;}
    else{cout<<p.first<<endl;}
    
    
   
    
    
}