import std.stdio, std.algorithm, std.array, std.ascii;

int main() {
	char a = scanChar();
	if('a'<=a && a<='z') {
		writeln("a");
	} else {
		writeln("A");
	}
	return 0;
} 

char scanChar() {
	import std.ascii;
	int c = ' ';
	while(isWhite(c) && c != -1) {
		c = getchar;
	}
	return cast(char)c;
	
}