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

const main = arg => {
    arg = arg.trim().split("\n");
    const A = (arg[0].split(" ")[0]);

    console.log(isUpperCase(A) ? "A" : "a");
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));