import sys

def find(needle, haystack):
    for c in needle:
        if haystack.find(c) >= 0:
            return True
    return False

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

n = sys.stdin.readline().strip()
password = sys.stdin.readline().strip()

min1 = 0
if len(password) < 6:
    min1 = 6 - len(password)

min2 = 0
if not find(numbers, password):
    min2 = min2 + 1

if not find(lower_case, password):
    min2 = min2 + 1

if not find(upper_case, password):
    min2 = min2 + 1

if not find(special_characters, password):
    min2 = min2 + 1

if min1 < min2:
    print min2
else:
    print min1