#include <cmath>
#include <cstdio>
#include <vector>
#include <set>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    
    set<char> charSets[4];
    string  numbers = "0123456789",
            lower_case = "abcdefghijklmnopqrstuvwxyz",
            upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
            special_characters = "!@#$%^&*()-+";
    for (int i = 0; i < numbers.length(); i++) charSets[0].insert(numbers[i]);
    for (int i = 0; i < lower_case.length(); i++) charSets[1].insert(lower_case[i]);
    for (int i = 0; i < upper_case.length(); i++) charSets[2].insert(upper_case[i]);
    for (int i = 0; i < special_characters.length(); i++) charSets[3].insert(special_characters[i]);
    
    bool contains[4] = {false};
    
    int n; cin >> n;
    string s; cin >> s;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < 4; j++) 
        {
            if (contains[j]) continue;
            if (charSets[j].end() != charSets[j].find(s[i])) contains[j] = true;
        }
    }
    
    int ans = 4;
    for (int j = 0; j < 4; j++) 
        if (contains[j]) ans--;
    
    ans = (6-n) > ans ? (6-n) : ans;
    cout << ans << endl;
    
    return 0;
}