process.stdin.resume();
process.stdin.setEncoding('utf8');

var g_input = '';
process.stdin.on('data', function(chunk) {
    g_input += chunk;
});

process.stdin.on('end', function() {
    Main(g_input.split(/\r?\n/));
});

function Main(input) {
    var line = input[0].split(' ');
    var x = parseInt(line[0]);
    var a = parseInt(line[1]);
    var b = parseInt(line[2]);

    if (Math.abs(x - a) <= Math.abs(x - b)) {
        console.log('A');
    }
    else {
        console.log('B');
    }
}

