#!/bin/python

import sys

def containsAtLeastOne(chars, password):
    for c in chars:
        if c in password:
            return True
    return False

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    ans = 0
    if not containsAtLeastOne(numbers, password):
        ans += 1
    if not containsAtLeastOne(lower_case, password):
        ans += 1
    if not containsAtLeastOne(upper_case, password):
        ans += 1
    if not containsAtLeastOne(special_characters, password):
        ans += 1
    if n + ans < 6:
        ans = 6-n
    return ans
    
if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer