// Try AtCoder
/// author: Leonardone @ NEETSDKASU
import std.stdio    : readln, writeln;
import std.string   : chomp;
import std.array    : split;
import std.conv     : to;
import std.typecons : Tuple;
import std.math     : abs;

auto getVals(T)() { return readln.chomp.split.to!(T[]); }

void main() {
    Tuple!(int,"x",int,"a",int,"b") t = getVals!int()[0..3];
    writeln(abs(t.x - t.a) < abs(t.x - t.b) ? "A" : "B");
}