#include <bits/stdc++.h>
using namespace std;

int main() {
  vector<tuple<int, int, char>> brothers(3);
  cin >> get<0>(brothers.at(0)) >> get<1>(brothers.at(0));
  cin >> get<0>(brothers.at(1)) >> get<1>(brothers.at(1));
  cin >> get<0>(brothers.at(2)) >> get<1>(brothers.at(2));

  get<2>(brothers.at(0)) = 'A';
  get<2>(brothers.at(1)) = 'B';
  get<2>(brothers.at(2)) = 'C';

  for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 2 - i; j++) {
      if (get<0>(brothers.at(j)) < get<0>(brothers.at(j + 1)) ||
          (get<0>(brothers.at(j)) == get<0>(brothers.at(j + 1)) &&
          get<1>(brothers.at(j)) > get<1>(brothers.at(j + 1))))
          swap(brothers.at(j), brothers.at(j + 1));
    }
  }

  for (tuple<int, int, char> t : brothers)
    cout << get<2>(t) << endl;
}