import core.bitop, std.bitmanip;
import core.checkedint;
import std.algorithm, std.functional, std.meta;
import std.array, std.container;
import std.bigint;
import std.conv;
import std.math, std.numeric;
import std.range, std.range.interfaces;
import std.stdio, std.string;
import std.ascii, std.typecons;

void main()
{
    char c;
    readf("%s", &c);
    readln;

    if (isUpper(c)) { writeln('A'); }
    else { writeln('a'); }
}