#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0; i<(n); i++)
#define REP2(i,x,n) for(int i=x; i<(n); i++)
#define ALL(n) begin(n),end(n)
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
vector<vector<int>> memo( 100 + 1, vector<int>( 10000 + 1, -1 ) );
int main()
{
    map<int, int> mp;
    REP( i, 3 )
    {
        int h;
        cin >> h;
        mp.emplace( h, i );
    }
    for ( auto it = mp.crbegin(); it != mp.crend(); it++ )
    {
        cout << ( (*it).second == 0 ? "A" : (*it).second == 1 ? "B" : "C" ) << endl;
    }
    return 0;
}