function Main(input) {
  const a = input;

  const s = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  let e = false;

  for (let i = 0; i < s.length; i++) {
    if (a === s[i]) {
      e = true;
    }
  }

  if (e) {
    console.log("A");
  } else {
    console.log("a");
  }
}

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