#include <iostream>
#include <climits>
using namespace std;
typedef long long ll;
int main(){
  int x1,y1,x2,y2,x3,y3;
  cin>>x1>>y1;
  cin>>x2>>y2;
  cin>>x3>>y3;
  int x,y,p;
  if(y1<=y2){
    if(y1<=y3){
      y=y1;
      x=x1;
      p=1;
    }
  } else {
    if(y2<=y3){
      y=y2;
      x=x2;
      p=2;
    } else {
      y=y3;
      x=x3;
      p=3;
    }
  }
  int o,e;
  o=0;
  e=0;
  if(y1%2==0){
    if(x1%2==0){
      e++;
    } else {
      o++;
    }
  }
  if(y2%2==0){
    if(x2%2==0){
      e++;
    } else {
      o++;
    }
  }
  if(y3%2==0){
    if(x3%2==0){
      e++;
    } else {
      o++;
    }
  }
  if(o>0 && e>0){
    cout<<-1<<endl;
    return 0;
  }
  ll i,z;
  i=0;
  while(1){
    if(i==LLONG_MAX){
      cout<<-1<<endl;
      break;
    }
    z=y*i+x;
    if(p==1){
      if(z%y2==x2 && z%y3==x3){
        cout<<z<<endl;
        break;
      }
    } else if(p==2){
      if(z%y1==x1 && z%y3==x3){
        cout<<z<<endl;
        break;
      }
    } else if(p==3){
      if(z%y1==x1 && z%y2==x2){
        cout<<z<<endl;
        break;
      }
    }
    i++;
  }
  return 0;
}