"use strict";

const isUpperCase = str => {
    return str === str.toUpperCase() ? true : false;
}

const main = (input) => {
    const spi = input.split('\n');
    const a = spi[0];

    console.log(isUpperCase(a) ? "A" : "a");
};

main(require("fs").readFileSync("/dev/stdin", "utf8"));
