#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000000
	

int main(){	
	
	string a,b,c,d,e,f;
	cin>>a>>b>>c>>d>>e>>f;
	
	if(b==e){
		cout<<-1<<endl;
	}
	else{
		if(b.size()>e.size()||(b.size()==e.size()&&b>e)){
			cout<<a<<endl;
		}
		else cout<<d<<endl;
	}
		
	
	return 0;
	
}