#include<bits/stdc++.h>
using namespace std;
int main(){
    string n[2],p[2],r[2];
    for(int i=0;i<2;i++)cin>>n[i]>>p[i]>>r[i];

    if(p[0].size()<p[1].size())cout<<n[1]<<endl;
    else if(p[0].size()>p[1].size())cout<<n[0]<<endl;
    else{
        if(p[0]==p[1])cout<<-1<<endl;
        else if(p[0]<p[1])cout<<n[1]<<endl;
        else cout<<n[0]<<endl;
    }

    return 0;
}