#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main() {
	vector<int> H(3);
	cin >> H[0] >> H[1] >> H[2];
	int A = H[0];
	int B = H[1];
	sort(H.begin(), H.end());
	for (int i = 2; i > -1; i--) {
		if (H[i] == A) {
			cout << 'A' << endl;
		}
		else if (H[i] == B) {
			cout << 'B' << endl;
		}
		else {
			cout << 'C' << endl;
		}
	}
}