#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    // Return the minimum number of characters to make the password strong
    map<string , int > m;
    
    m["number"]=0;
    m["upper"]=0;
    m["lower"]=0;
    m["special"]=0;
    
    for(int i=0;i<n;i++)
    {
        if(s[i]>='0'&&s[i]<='9')
            m["number"]++;
        if(s[i]>='a'&&s[i]<='z')
            m["lower"]++;
        
        if(s[i]>='A'&&s[i]<='Z')
            m["upper"]++;
      
       else if(s[i]=='!')
            m["special"]++;
        else if(s[i]=='#')
            m["special"]++;
        else if(s[i]=='@')
            m["special"]++;
        else if(s[i]=='$')
            m["special"]++;
        else if(s[i]=='^')
            m["special"]++;
        else if(s[i]=='&')
            m["special"]++;
        else if(s[i]=='*')
            m["special"]++;
        else if(s[i]=='(')
            m["special"]++;
        else if(s[i]==')')
            m["special"]++;
        else if(s[i]=='-')
            m["special"]++;
        else if(s[i]=='+')
            m["special"]++;
    }
    
    int count=0;
    
    if(m["number"]<=0)
        count++;
    if(m["lower"]<=0)
        count++;
    if(m["upper"]<=0)
        count++;
    if(m["special"]<=0)
        count++;
    
    if(n>=6)
        return count;
    else
    {
        if(n+count>=6)
            return count;
        else
            return count+(6-n-count);
    }
}

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