#include <iostream>
#include <string>
#define MOD 1000000007
#define INF 11234567890
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

std::string Sa, Sb, Pa, Pb, Xa, Xb;

int main()
{
	in >> Sa >> Pa >> Xa >> Sb >> Pb >> Xb;

	if (Pa.length() > Pb.length()) { out << Sa << std::endl; }
	else if (Pa.length() < Pb.length()) { out << Sb << std::endl; }
	else
	{
		bool flag = false;
		rep(i, Pa.length())
		{
			if ((Pa[i] - '0') > (Pb[i] - '0'))
			{
				out << Sa << std::endl;
				flag = true;
				break;
			}
			if ((Pa[i] - '0') < (Pb[i] - '0'))
			{
				out << Sb << std::endl;
				flag = true;
				break;
			}
		}
		if (!flag) { out << -1 << std::endl; }
	}
	return 0;
}