#!/bin/python

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 = "!@#$%^&*()-+"

result = [0,0,0,0]

for char in password:

if char in numbers:

result[0] += 1

if char in lower_case:

result[1] += 1

if char in upper_case:

result[2] += 1

if char in special_characters:

result[3] += 1

#print result

if n + result.count(0) < 6:

return result.count(0) + (6-n-result.count(0))

else:

return result.count(0)

if __name__ == "__main__":

n = int(raw_input().strip())

password = raw_input().strip()

answer = minimumNumber(n, password)

print answer