#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
string s;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> s;
  if (isupper(s[0]))
    cout << "A\n";
  else
    cout << "a\n";
  return 0;
}
