#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    // Return the minimum number of characters to make the password strong
    int i;
    int c2=0,c3=0,c4=0,c5=0;
    
    for(i=0;i<n;i++)
    {
        
        if(s[i]>='a'&&s[i]<='z')
            c2=1;
        else if(s[i]>='A'&&s[i]<='Z')
            c3=1;
        else if(s[i]>='0'&&s[i]<='9')
            c4=1;
        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]=='+')
            c5=1;
            
        
    }
    int t=4-(c2+c3+c4+c5);
    int t2=6-n;
    if(t2>t)
        return t2;
    else 
        return t;
    
}

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