#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) {
    int i, k, num = 0, l = 0, u = 0, s = 0, c = 0, res;
    for(i = 0; i < n; i++)
    {
        k = (int)password[i];
        if(48 <= k && k <= 57) num++;
        if(97 <= k && k <= 122) l++;
        if(65 <= k && k <= 90) u++;
        if(33 <= k && k <= 47) s++;
        if(k == 64 || k == 94 ) s++;
    }
    
    if(num != 0) c++;
    if(l != 0) c++;
    if(u != 0) c++;
    if(s != 0) c++;
    
    res = 4 - c;
    
    if(n + res < 6) res = 6 - n;
    
    return res;
    
}

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;
}