#include <iostream>
using namespace std;

int main() {
    for (int i = 0;i < 3;i++) {
        int arr[4];
        for (int j = 0;j < 4;j++) {
            cin >> arr[j];
        }
        int b = 0;
        int d = 0;
        for (int j = 0;j < 4;j++) {
            if (arr[j] == 1) {
                d++;
            }
            else{
                b++;
            }
        }
        if (b == 1) {
            cout << "A";
        }
        else if (b == 2) {
            cout << "B";
        }
        else if (b == 3) {
            cout << "C";
        }
        else if (b == 4) {
            cout << "D";
        }
        else if (d == 4) {
            cout << "E";
        }
        cout << "\n";
    }
    return 0;
}