#include <iostream>
#include <vector>
using namespace std;
//8-4-2-1
int main(){
    vector<char> win;
    for (int i='A';i<='O';++i){
        win.push_back(char(i));
    }
    vector<char> win1;
    for (int i=1;i<=8;++i){
        int a,b;
        scanf("%d-%d",&a,&b);
        if (a>b){
            win1.push_back(win[i*2-2]);
        }else{
            win1.push_back(win[i*2-1]);
        }
    }
    vector<char> win2;
    for (int i=1;i<=4;++i){
        int a,b;
        scanf("%d-%d",&a,&b);
        if (a>b){
            win2.push_back(win1[i*2-2]);
        }else{
            win2.push_back(win1[i*2-1]);
        }
    }
    vector<char> win3;
    for (int i=1;i<=2;++i){
        int a,b;
        scanf("%d-%d",&a,&b);
        if (a>b){
            win3.push_back(win2[i*2-2]);
        }else{
            win3.push_back(win2[i*2-1]);
        }
    }
    vector<char> win4;
    for (int i=1;i<=1;++i){
        int a,b;
        scanf("%d-%d",&a,&b);
        if (a>b){
            win4.push_back(win3[i*2-2]);
        }else{
            win4.push_back(win3[i*2-1]);
        }
    }
    vector<char> win5;
    for (int i=1;i<=1;++i){
        int a,b;
        scanf("%d-%d",&a,&b);
        if (a>b){
            win5.push_back(win4[i*2-2]);
        }else{
            win5.push_back(win4[i*2-1]);
        }
    }
    cout<<win5[0];
    return 0;
}