#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* password) {
    // Return the minimum number of characters to make the password strong
    
    int len = strlen(password);
    int u=0, l=0, spl=0, dig=0,set=0;
    for(int i=0; i<len ; i++)
    {
        if(password[i] >= 'a' && password[i] <= 'z' )
            l=1;
        else if(password[i] >= 'A' && password[i] <= 'Z' )
            u=1;
        else if(password[i] >= '0' && password[i] <= '9' )
            dig=1;
        else
            spl=1;
    }
    if(u==1)
        set++;
    if(l==1)
        set++;
    if(dig==1)
        set++;
    if(spl==1)
        set++;
    
    if(set == 1)
        if(n <= 6)
            if(6-n > 3)
                return 6-n;
            else
                return 3;
        else
            return 3;
    
    
        
    if(set == 2)
        if(n <= 6)
            if(6-n > 2)
                return 6-n;
            else
                return 2;
        else
            return 2;
    if(set == 3)
        if(n <= 6)
            if(6-n > 1)
                return 6-n;
            else
                return 1;
        else
            return 1;
    
    if(set == 4)
        if(n <= 6)
            if(6-n > 0)
                return 6-n;
            else
                return 0;
        else
            return 0;
    else return 0;
    
}

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;
}