#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <map>
#include <cstring>

int main() {
    std::map<char, int> numbers;
    std::map<char, int> lowerLetters;
    std::map<char, int> upperLetters;
    std::map<char, int> specialCharacters;
    int n;
    std::string s;
    
    std::cin >> n;
    std::cin >> s;
    
    for (int i = 0; i < s.size(); i++) {
        if (strchr("0123456789", s[i])) {
            numbers[s[i]]++;  
        } else if (strchr( "abcdefghijklmnopqrstuvwxyz", s[i])) {
            lowerLetters[s[i]]++;
        } else if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ", s[i])) {
            upperLetters[s[i]]++;
        } else {
            specialCharacters[s[i]]++;
        }
    }
    
    int neededChars = 0;
    if (numbers.size() == 0) {
        neededChars++;
    }
    if (lowerLetters.size() == 0) {
        neededChars++;
    }
    if (upperLetters.size() == 0) {
        neededChars++;
    }
    if (specialCharacters.size() == 0) {
        neededChars++;
    }
    
    if (n + neededChars > 6) {
        std::cout << neededChars << std::endl;
    } else {
        std::cout << 6 - n;
    }

    return 0;
}