import std.algorithm;
import std.range;
import std.stdio;
import std.math;
import std.array;
import std.string;
import std.conv;

/// 数列の読み込み
auto readNums() {
	return readln().chomp.split.map!(to!int);
}

void main() {
	auto nums = readNums();
	immutable x = nums[0];
	immutable a = nums[1];
	immutable b = nums[2];
	writefln("%s", abs(x - a) < abs(x - b) ? 'A' : 'B');
}
