#include<bits/stdc++.h>
using namespace std;
int a,b;
int main(){
	scanf("%d-%d",&a,&b);
	char win1=(a>b)?'A':'B';
	scanf("%d-%d",&a,&b);
	char win2=(a>b)?'C':'D';
	scanf("%d-%d",&a,&b);
	char win3=(a>b)?'E':'F';
	scanf("%d-%d",&a,&b);
	char win4=(a>b)?'G':'H';
	scanf("%d-%d",&a,&b);
	char win5=(a>b)?'I':'J';
	scanf("%d-%d",&a,&b);
	char win6=(a>b)?'K':'L';
	scanf("%d-%d",&a,&b);
	char win7=(a>b)?'M':'N';
	scanf("%d-%d",&a,&b);
	char win8=(a>b)?'O':'P';
	scanf("%d-%d",&a,&b);
	char win2_1=(a>b)?win1:win2;
	scanf("%d-%d",&a,&b);
	char win2_2=(a>b)?win3:win4;
	scanf("%d-%d",&a,&b);
	char win2_3=(a>b)?win5:win6;
	scanf("%d-%d",&a,&b);
	char win2_4=(a>b)?win7:win8;
	scanf("%d-%d",&a,&b);
	char win3_1=(a>b)?win2_1:win2_2;
	scanf("%d-%d",&a,&b);
	char win3_2=(a>b)?win2_3:win2_4;
	scanf("%d-%d",&a,&b);
	char win4_1=(a>b)?win3_1:win3_2;
	printf("%c\n",win4_1);
	return 0;
}