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

has = [0, 0, 0, 0]

n = int(input())
s = input()

for l in s:
    if l in numbers:
        has[0] = 1
    elif l in lower_case:
        has[1] = 1
    elif l in upper_case:
        has[2] = 1
    elif l in special_characters:
        has[3] = 1

to_add = 0
for x in has:
    if not x:
        to_add += 1
        n += 1



if n < 6:
    print(6-n+to_add)
else:
    print(to_add)