#include <cstdio>
#include <string>

using namespace std;


bool criteriasMet[4];

int main() {
  
  string numbers = "0123456789";
  string lower_case = "abcdefghijklmnopqrstuvwxyz";
  string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  string special_characters = "!@#$%^&*()-+";
  
  int n;
  char pass[101];
  scanf("%d", &n);
  scanf("%s", pass);
  
  
  for (int i = 0; i < n; ++i) {
    char c = pass[i];
    if (numbers.find(c) != string::npos) {
      criteriasMet[0] = true;
    } else if (lower_case.find(c) != string::npos) {
      criteriasMet[1] = true;
    } else if (upper_case.find(c) != string::npos) {
      criteriasMet[2] = true;
    } else if (special_characters.find(c) != string::npos) {
      criteriasMet[3] = true;
    }
  }
  
  int sum = 0;
  for (int i = 0; i < 4; ++i) {
    if (criteriasMet[i]) {
      sum++;
    }
  }
  int result = (4 - sum);
  printf("%d\n", max(result, 6 - n));
  return 0;
}