#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    int a[4]={0};
    int k=0,i=0,l=0;
    if(n<6)
    {
        l=6-n;
    }
    for(i=0;i<n;i++)
    {
        if(s[i]>=48 && s[i]<=57)
            a[0]++;
        else if(s[i]>=65 && s[i]<=90)
            a[1]++;
        else if(s[i]>=97 && s[i]<=122)
            a[2]++;
        else if(s[i]=='!' || s[i]=='@' || s[i]=='#' || s[i]=='$'||s[i]=='%'||s[i]=='^'||s[i]=='&'||s[i]=='*'||s[i]=='('||s[i]==')'||s[i]=='-'||s[i]=='+')
            a[3]++;
    }
    for(i=0;i<4;i++)
    {
        if(a[i]==0)
            k++;
    }
    if(l<k)
        return k;
    else
        return l;
    // Return the minimum number of characters to make the password strong
}

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