'use strict';

function Main(INPUT) {
    const input = INPUT.split("\n")[0].split(" ").map(n => Number(n));
    const x = input[0];
    const a = input[1];
    const b = input[2];
    if (Math.abs(x - a) < Math.abs(x - b)) {
        console.log("A");
    } else {
        console.log("B");
    }
}

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