#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    f1=0
    f2=0
    f3=0
    f4=0
    for i in range(n):
        if password[i] in numbers:
            f1=1
        if password[i] in lower_case:
            f2=1
        if password[i] in upper_case:
            f3=1
        if password[i] in special_characters:
            f4=1
    if n<6:
        return max(4-(f1+f2+f3+f4),6-n)
    return 4-(f1+f2+f3+f4)
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)