#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,a1=0,a2=0,a3=0,a4=0;
    for(i=0;i<n;i++)
    {
        if(password[i]>=48 && password[i]<=57)
            a1=1;
        if(password[i]>=97  && password[i]<=122)
            a2=1;
        if(password[i]>=65  && password[i]<=90)
            a3=1;
        if(password[i]=='!' || password[i]=='@' || password[i]=='#' || password[i]=='$' || password[i]=='%' || password[i]=='^' || password[i]=='&' || password[i]=='*' || password[i]=='(' || password[i]==')' || password[i]=='-' || password[i]=='+')
            a4=1;        
    }
    int sum=a1+a2+a3+a4;
        if(n>=6 && sum==4)
            return 0;
        else
            if((4-sum)>(6-n))
                return 4-sum;
        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;
}