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

int minimumNumber(int n, char* password) {
    int i;
    int a=0,b=0,c=0,d=0;
    for(i=0;i<n;i++)
    {
        if(islower(password[i]))
            a=1;
        else if(isupper(password[i]))
            b=1;
        else if(isdigit(password[i]))
            c=1;
        else
            d=1;
    }
    int k=4-a-b-c-d;
    if(n+k<6)
        k+=6-n-k;
    return k;
    
}

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;
}