function main(input) {
  input = input.trim();
  const a = input.split(" ").map(Number);
  const b = a[2] - a[0];
  const c = a[1] - a[0];
  if(a[0]>a[1]){
    c = c*(-1);
  }
  if(c<b){
    console.log("A");
  }else{
    console.log("B");
  }
    
}
main(require("fs").readFileSync("/dev/stdin", "utf8"));
