"use strict";

function Main(input) {
    // 1行目がinput[0], 2行目がinput[1], …に入る
    input = input.split("\n");
    let alpha = input[0];

    //出力
    if (isUpperCase(alpha)) {
        console.log('A');
    } else {
        console.log('a');
    }
}

const isUpperCase = c => {
    return /^[A-Z]+$/g.test(c)
}

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