#include <iostream>
using namespace std;

int minimumNumber(int n, char p[]) {
    register int i;
    int cap=0,sm=0,dig=0,sp=0,c=0;
    for(i=0;i<n;i++)
    {
        if(p[i]>=65 && p[i]<=90)
        cap++;
        else
        if(p[i]>=97 && p[i]<=122)
        sm++;
        else
        if(p[i]>=48 && p[i]<=57)
        dig++;
        else
        if(p[i]=='!' || p[i]=='@' ||p[i]=='#' || p[i]=='$' || p[i]=='%' || p[i]=='^' ||p[i]=='&' ||p[i]=='*' || p[i]=='(' ||p[i]==')' || p[i]==')' || p[i]=='-' || p[i]=='+')
        sp++;
        if(cap && sm && dig && sp)
        break;
    }
    c=!cap+!sm+!dig+!sp;
    if(n>=6)
    return c;
    else 
    { 
        if(c+n>=6)
        return c;
        else
        return 6-n; 
    }
}

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