//: 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.characters{
    if itr == " "{
        array.append(Int(temp) ?? 0)
        temp = "";
    } else {
        temp += String(itr);
    }
}
array.append(Int(temp) ?? 0)
if  abs(array[0]-array[1]) < abs(array[0]-array[2]){
    print("A")
}else{
    print("B")
}

