import std.stdio, std.string, std.conv, std.bigint, std.typecons, std.algorithm, std.array, std.math, std.range, std.functional;
 
void main() {
    auto tmp = readln.split.to!(int[]);
    writeln(abs(tmp[0] - tmp[1]) < abs(tmp[0] - tmp[2]) ? "A" : "B");
}