characters = ["0123456789", "abcdefghijklmnopqrstuvwxyz", "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "!@#$%^&*()-+"]
n = int(input())
satistied = [False, False, False, False]
count = 4
s = input()
for character in s:
    for i in range(4):
        if not satistied[i] and character in characters[i]:
            count -= 1
            satistied[i] = True
print(max(count, 6-n))