unittest
{
	assert( [ "5 2 7" ].parse.expand.solve == "B" );
	assert( [ "1 999 1000" ].parse.expand.solve == "A" );
}



import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

void main()
{
	stdin.byLineCopy.parse.expand.solve.writeln;
}

auto parse( Range )( Range input )
if( isInputRange!Range && is( ElementType!Range == string ) )
{
	auto xab = input.front.split.to!( long[] );
	return tuple( xab[ 0 ], xab[ 1 ], xab[ 2 ] );
}

auto solve( long x, long a, long b )
{
	auto xa = ( x - a ).abs;
	auto xb = ( x - b ).abs;
	return ( xa < xb ) ? "A" : "B";
}
