#include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    cin >> n;
    string str;
    cin >> str;
    set<int> myset;
    int len = str.length();
    for(int i=0;i<n;i++){
        if(str[i]-'0'>=0 && str[i]-'0'<=9){
            myset.insert(1);
        }
        else if(str[i]-'a'>=0 && str[i]-'a'<=25){
            myset.insert(2);
        }
        else if(str[i]-'A'>=0 && str[i]-'A'<=25){
            myset.insert(3);
        }
        else if( (str[i]=='!') || (str[i]=='@') || (str[i]=='#') || (str[i]=='$') || (str[i]=='%') || (str[i]=='^') || (str[i]=='&') || (str[i]=='*') || (str[i]=='(') || (str[i]==')') || (str[i]=='-') || str[i]=='+' ){
            myset.insert(4);
        }
    }
    int ans = 4-myset.size();
    if(n+ans<6){
        ans += (6-n-ans);
    }
    cout << ans << endl;
    return 0;
}