function main(input) {
  input=input.trim();
  const x = parseInt(input.split(" ")[0], 10);
  const a = parseInt(input.split(" ")[1], 10);
  const b = parseInt(input.split(" ")[2], 10);

  if(Math.abs(x-a)>Math.abs(x-b)){
    console.log("B");
  }else{
    console.log("A");
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));