using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] sintyou = new int[3];
            int[] org = new int[3];
            for (int i = 0; i < 3; i++)
            {
                sintyou[i] = int.Parse(Console.ReadLine());
                org[i] = sintyou[i];
            }
            Array.Sort(sintyou);
            Array.Reverse(sintyou);
            for(int i=0;i<3;i++)
            {
                for(int j=0; j<3;j++)
                {
                    if (sintyou[i] == org[j])
                    {
                        if(j==0)
                        {
                            Console.WriteLine("A");
                        }
                        else if(j==1)
                        {
                            Console.WriteLine("B");
                        }
                        else
                        {
                            Console.WriteLine("C");
                        }
                    }
                }
            }
            
        }
    }
}