#include <iostream>
using namespace std;

int main () {
    unsigned a, b, c;
    while (cin >> a >> b >> c) {
        if      (a>b+c || c>a && a>b && a+b>c || b>a && a>c && a+c>b)
            cout << "A\n";
        else if (b>a+c || c>b && b>a && b+a>c || a>b && b>c && b+c>a)
            cout << "B\n";
        else
            cout << "C\n";
    }
}