#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <list>
#include <numeric>
using namespace std;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = 1<<25;
typedef pair<int,int> P;
typedef long long ll;
typedef unsigned long long ull;


int main(){
	char s[2][1000];
	int a[2];
	char c;
	for(int i = 0; i < 2; i++) scanf("%s %d %c", s[i], a+i, &c);
	if(a[0]==a[1]) puts("-1");
	else printf("%s\n", a[0]>a[1]?s[0]:s[1]);
	
	return 0;
}