#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()
{
    vector<tuple<int, int, int>> vc;
    REP( i, 3 )
    {
        int h, w;
        cin >> h >> w;
        vc.emplace_back( make_tuple( h, w, i ) );
    }
    sort( ALL( vc ), []( const auto &x, const auto &y )
         {
             return get<0>( x ) == get<0>( y ) ? get<1>( x ) < get<1>( y ) : get<0>( x ) > get<0>( y );
         });
    for( auto x : vc )
    {
        cout << ( get<2>( x ) == 0 ? "A" : get<2>( x ) == 1 ? "B" : "C" ) << endl;
    }
    return 0;
}