"use strict"

function main(input) {
  input = input.split(' ').map(v => ~~v)

  let ans = (Math.abs(input[1] - input[0]) < Math.abs(input[2] - input[0])) ? 'A' : 'B'
  console.log(ans)
}
main(require("fs").readFileSync("/dev/stdin", "utf8"))
