#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    int up=0,sp=0,lc=0,no=0,res=0;
    if(n<6)
        res=6-n;
        
    for(int i=0;i<n;i++)
    {
        if(int(s[i])>=65&&int(s[i])<=90)
            up++;
     if(int(s[i]>=97&&int(s[i])<=122))
        lc++;
     if(int(s[i]>=48&&int(s[i])<=57))
        no++;
     if(int(s[i]>=33&&int(s[i])<=47))
        sp++;
    }
    int res2=(!up+!lc+!no+!sp);
    return res2>res?res2:res;
    // Return the minimum number of characters to make the password strong
}

int main() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    int answer = minimumNumber(n, s);
    cout << answer << endl;
    return 0;
}