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

n=int(raw_input())
x=raw_input()
c=4
for st in (numbers,lower_case,upper_case,special_characters):
    for i in x:
        if i in st:
            c-=1
            break
print max(c,6-len(x))