#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
char numbers[] = "0123456789";
char lower_case[] = "abcdefghijklmnopqrstuvwxyz";
char upper_case[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char special_characters[] = "!@#$%^&*()-+";
    int check_character(char c)
{
    char i;
    for(i=0;i<10;i++)
    {
        if(c == numbers[i])
            return 1;
    }
    if(c<='z'  &&  c>='a')
        return 2;
    if(c<='Z'  &&  c>='A')
        return 3;
    for(i=0;i<12;i++)
    {
        if(c == special_characters[i])
            return 4;
    }
    return 0;
}

int minimumNumber(int n, char* password) {
    int up_flag=0;
    int low_flag=0;
    int num_flag=0;
    int special_flag=0;
    int value;
    int i;
    for(i=0;i<n;i++)
    {
        value = check_character(password[i]);
        //printf("%d\n",value);
        switch (value)
        {
            case 1: num_flag=1; break;
            case 2: low_flag=1; break;
            case 3: up_flag=1;  break;
            case 4: special_flag=1; break;
            default: break;
        }
    }
    value = 4 - (up_flag+low_flag+num_flag+special_flag);
    //printf("value=%d  %d\n",value,6-n);
    if(value>= (6-n))
        return value;
    else
        return (6-n);
    
}

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;
}