#!/bin/python3

import sys

numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"

def minimumNumber(n, password):
    hasUpper = False
    hasLower = False
    hasSpecial = False
    hasNumber = False
    for c in password:
        if not hasUpper and c in upper_case:
            hasUpper = True
        elif not hasLower and c in lower_case:
            hasLower = True
        elif not hasSpecial and c in special_characters:
            hasSpecial = True
        elif not hasNumber and c in numbers:
            hasNumber = True
    # Return the minimum number of characters to make the password strong
    missingChars = sum([0 if x else 1 for x in [hasUpper, hasLower, hasSpecial, hasNumber]])
    return max(missingChars, 6 - n)

if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)