unittest
{
	assert( [ "B" ].solve == "A" );
	assert( [ "a" ].solve == "a" );
}



import std.conv;
import std.range;
import std.stdio;

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

auto solve( Range )( Range input )
if( isInputRange!Range && is( ElementType!Range == string ) )
{
	auto s = input.front.to!( dchar[] );
	
	if( 'A' <= s.front && s.front <= 'Z' ) return "A";
	else                                   return "a";
}
