numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"
n = int(input())
string = [str(i) for i in input()]
boo_n = boo_l = boo_u = boo_s = False
for i in range(n):
    if string[i] in numbers:
        boo_n = True
    if string[i] in lower_case:
        boo_l = True
    elif string[i] in upper_case:
        boo_u = True
    elif string[i] in special_characters:
        boo_s = True
ans = 4 - (boo_l + boo_u + boo_s + boo_n) if 4-(boo_l + boo_u + boo_s + boo_n) + n >= 6 else 6 - n
print(ans)