#include <bits/stdc++.h>

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define FOR(i,n,m) for(int i=(int)(n); i<=(int)(m); i++)
#define RFOR(i,n,m) for(int i=(int)(n); i>=(int)(m); i--)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define RITR(x,c) for(__typeof(c.rbegin()) x=c.rbegin();x!=c.rend();x++)
#define setp(n) fixed << setprecision(n)

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

#define ll long long
#define vll vector<ll>
#define vi vector<int>
#define pll pair<ll,ll>
#define pi pair<int,int>

#define all(a) (a.begin()),(a.end())
#define rall(a) (a.rbegin()),(a.rend())
#define fi first
#define se second
#define pb push_back
#define ins insert

#define debug(a) cerr<<(a)<<endl
#define dbrep(a,n) rep(_i,n) cerr<<(a[_i])<<" "; cerr<<endl
#define dbrep2(a,n,m) rep(_i,n){rep(_j,m) cerr<<(a[_i][_j])<<" "; cerr<<endl;}

using namespace std;

template<class A, class B>
ostream &operator<<(ostream &os, const pair<A,B> &p){return os<<"("<<p.fi<<","<<p.se<<")";}
template<class A, class B>
istream &operator>>(istream &is, pair<A,B> &p){return is>>p.fi>>p.se;}

pair<ll,ll> crt(const vll& r,const vll& m) {
  assert(r.size()==m.size());
  int n=int(r.size());
  //Contracts: 0 <=r0 < m0
  ll r0=0,m0=1;
  for(int i=0;i<n;++i){
    assert(1<=m[i]);
    ll r1=r[i]%m[i],m1=m[i];
    if(m0<m1){
      swap(r0,r1);
      swap(m0,m1);
    }
    if(m0%m1==0){
      if(r0%m1!=r1)return {0,0};
      continue;
    }
    ll a=m0%m1;
    if(a<0)a+=m1;
    ll g=m1,im=0;

    if(a){
      ll ims=1;
      while(a){
        ll u=g/a;
        g-=a*u;
        im-=ims*u;
        auto tmp=g;g=a;a=tmp;
        tmp=im;im=ims;ims=tmp;
      }
      if(im<0)im+=m1/g;
    }
    ll u1=(m1/g);
    if((r1-r0)%g) return {0,0};
    ll x=(r1-r0)/g%u1*im%u1;
    r0+=x*m0;
    m0*=u1;
    if(r0<0) r0+=m0;
  }
  return {r0,m0};
}

//-------------------------------------------------

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    vll x(3),y(3);
    rep(i,3) cin>>x[i]>>y[i];
    auto res = crt(x,y);
    if (res.se==0){
        cout<<"-1\n";
    }else{
        if (res.fi>0){
            cout<<res.fi<<"\n";
        }else{
            cout<<res.se<<"\n";
        }
    }
    return 0;
}