#include<iostream>
using namespace std;
long gcd(long a,long b){return b?gcd(b,a%b):a;}
main()
{
	long X,Y;
	cin>>X>>Y;
	if(X==0)X=Y;
	for(int _=0;_<2;_++)
	{
		long x,y;cin>>x>>y;
		for(int i=0;i<y;i++)
		{
			if(X%y==x)break;
			X+=Y;
		}
		if(X%y!=x)
		{
			cout<<-1<<endl;
			return 0;
		}
		Y=Y/gcd(Y,y)*y;
	}
	cout<<X<<endl;
}