//: Playground - noun: a place where people can play


import Foundation
/*
func readInt(str : String) -> Int{
    return Int(str)  ?? 0
}

func splitInt(str : String,array :inout [Int]) ->(){
    var temp : String = ""
    for itr in str{
        if itr == " "{
            array.append(Int(temp) ?? 0)
            print(temp)
            temp =  ""
        } else {
            temp += String(itr)
        }
    }
    array.append(Int(temp) ?? 0)
}
*/

var str: String = readLine() ?? ""
var array :[Int] = []
let startindex = str.startIndex
var temp:String = ""
var index = startindex
for itr in str{
    if itr == " "{
        array.append(Int(temp) ?? 0);
        temp = "";
    } else {
        temp += String(itr);
    }
}
if  abs(array[0]-array[1]) > abs(array[0]-array[2]){
    print("A")
}else{
    print("B")
}


