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

bool contains(string str, char what) {
    for(int i = 0; i < str.size(); i++) {
        
        if(what == str[i]) {
      //      cout << "what(" << what << ")=str[i](" << str[i] << ")" << endl;
            return true;
        } else {
          //  cout << "what(" << what << ")!=str[i](" << str[i] << ")" << endl;
        }
    }
    return false;
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n;
    cin >> n;
    string str;
    cin >> str;
    
    vector<bool> criterions;
    int quantity = 6;
    string numbers = "0123456789";
    string lower_case = "abcdefghijklmnopqrstuvwxyz";
    string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string special_characters = "!@#$%^&*()-+";
    
    for(int i = 0; i < 5; i++){
        criterions.push_back(false);
    }
    
    if(n >= quantity) {
        criterions[0] = true;
    }
    for(int i = 0; i < n; i++) {
        if(!criterions[1]) {
            if(contains(numbers,str[i])) {
                criterions[1] = true;
            }
        }
        if(!criterions[2])  {
            if(contains(lower_case,str[i])) {
                criterions[2] = true;
            }
        }
        if(!criterions[3])
        {
            if(contains(upper_case,str[i])) {
                criterions[3] = true;
            }
        }
        
        if(!criterions[4])
        {
            if(contains(special_characters,str[i])) {
                criterions[4] = true;
            }
        }
      /*  for(int i = 1; i < criterions.size(); i++) {
            cout << "criterions[" << i << "]=" << criterions[i] << endl;
        }*/
        
    }
    int weakness = 0;
    for(int i = 1; i < criterions.size(); i++) {
        if(!criterions[i])
            weakness++;
    }
    
    int neh = 0;
    
    if(criterions[0] == false) {
        neh = quantity-str.size();
        if(neh < weakness)
            neh = weakness;
    } else  {
        neh = weakness;
    }
    
    cout << neh << endl;
    
    return 0;
}