#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

// #define DEBUG

int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int h, w;
    tuple<int, int, char> person[3];

    for (int i = 0; i < 3; i++){
        cin >> h >> w;
        person[i] = make_tuple(-h, w, 'A' + i);
    }

    sort(person, person + 3);
    cout << get<2>(person[0]) << endl;

    return 0;
}