#include <iostream>
#include <math.h>
#include <algorithm>
#include <functional>
#include <vector>
#include <typeinfo>
#include <climits>
#include <ctype.h>
#include <string>
#include <stdio.h>
using namespace std;
#define INIT cin.tie(0); ios::sync_with_stdio(false);
#define FOR(i, a, n) for (int i = a; i < n; i++)
#define REP(i, n) for(int i = 0; i < n; i++)

int main()
{
    INIT;

    vector<int> a, b;
    int tmp;
    REP(i, 3){
        cin >> tmp;
        a.push_back(tmp);
        b.push_back(tmp);
    }
    sort(b.begin(), b.end(), greater<int>());
    char H[3] = {'A', 'B', 'C'};
    REP(i, 3){
        REP(j, 3){
            if(b[i] == a[j]){
                cout << H[j] << endl;
                break;
            }
        }
    }

    return 0;
}