#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int minimumNumber(int n, char* str) {
    // Return the minimum number of characters to make the password strong
    int c=0,d=0,e=0,f=0;
    int c1=0,d1=0,e1=0,f1=0;
    if(n<6)
    {
        if(n<=2)
    return 6-n;
        else
        {
            for(int i=0;i<n;i++)
        {
            if(str[i] >= 48 && str[i]<=57)
            {
                c1=1;
            }
            else if(str[i] >=65 && str[i]<=90)
            {
                d1=1;
            }
            else if(str[i] >=97 && str[i]<=122)
            {
                e1=1;
            }
            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] == '!')
            {
                f1=1;
            }
        }
            int x=4-c1-d1-e1-f1;
            if(n==3)
            {
            if(x<=3)
                return 3;
            else    
                return x;
            }
            else if(n==4)
            {
                if(x<=2)
                    return 2;
                else
                    return x;
            }
            else if(n==5)
            {
                if(x<=1)
                    return 1;
                else
                    return x;
            }
            
        }
    }
    else
    {
        for(int i=0;i<n;i++)
        {
            if(str[i] >= 48 && str[i]<=57)
            {
                c=1;
            }
            else if(str[i] >=65 && str[i]<=90)
            {
                d=1;
            }
            else if(str[i] >=97 && str[i]<=122)
            {
                e=1;
            }
            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] == '!')
            {
                f=1;
            }
        }
    }
    
    return 4-c-d-e-f;
}

int main() {
    int n; 
    scanf("%i", &n);
    char* password = (char *)malloc(512000 * sizeof(char));
    scanf("%s", password);
    int answer = minimumNumber(n, password);
    printf("%d\n", answer);
    return 0;
}