#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll inf = LLONG_MAX;
const long double pi = acosl(-1);
void Yes() { cout << "Yes" << endl; }
void No() { cout << "No" << endl; }
void YES() { cout << "YES" << endl; }
void NO() { cout << "NO" << endl; }
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  char c;
  cin >> c;
  if (0 <= c - 'a' && c - 'a' <= 25)
    cout << "a" << endl;
  else
    cout << "A" << endl;
}
