#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* p) {
    // Return the minimum number of characters to make the password strong
    int a[4],i,m,count=0,min=0;
    if(n<6)
        min=6-n;
    for(i=0;i<4;i++)
        a[i]=0;
    for(i=0;i<n;i++)
    {
        m=p[i];
        if(m>=65 && m<=90)
            a[0]++;
        if(m>=97 && m<=122)
            a[1]++;
        if(m>=48 && m<=57)
            a[2]++;
        if(m=='!' || m=='@' || m=='#' || m=='$'  || m=='%' || m=='^' || m=='&' || m=='*' || m=='(' || m==')' || m=='-' || m=='+')
            a[3]++;
    }
    for(i=0;i<4;i++)
    {
        if(a[i]==0)
            count++;
    }
    if(min<count)
        min=count;
    return min;
}

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