'use strict'

function main(s) {

  s = s.split('\n')[0].split(' ').map(n => Number(n));
  const toA = Math.abs(s[0] - s[1]);
  const toB = Math.abs(s[0] - s[2]);
  const ans = (toA < toB) ? 'A' : 'B';

  console.log(ans);
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));
