#include <bits/stdc++.h>
using namespace std;

int f(const string &s) {
  const int n = s.size();
  int toadd = max(0, 6 - n), upper = 1, lower = 1, digit = 1, special = 1;
  for (char c : s) {
    if (isupper(c))
      upper = 0;
    else if (islower(c))
      lower = 0;
    else if (isdigit(c))
      digit = 0;
    else
      special = 0;
  }
  return max(toadd, upper + lower + digit + special);
}

int main() {
  int n;
  string s;
  cin >> n >> s;
  cout << f(s) << endl;
  return 0;
}