#include <iostream>
#include <set>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
#include <map>
#include <utility>
#include <list>
#include <climits>
#include <bitset>
#include <numeric>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)
#define repi(i, n) for(auto i = (n).begin(); i != (n).end(); i++)
#define in_arr(type, a, n) copy_n(istream_iterator<type>(cin), n, (a).begin());
#define ll long long int

int main(){
    int a, b, c;
    cin >> a >> b >> c;
    if(a < c && b < c){
        cout << "C" << endl;
    }else if(a < b){
        cout << "B" << endl;
    }else{
        cout << "A" << endl;
    }
    return 0;
}

