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

n = int(input())

str = input()

f1 = f2 = f3 = f4 = 0

for char in str:
    if char in numbers:
        f1 = 1
    elif char in lower_case:
        f2 = 1
    elif char in upper_case:
        f3 = 1
    else:
        f4 = 1
        
       
print(max(6 - len(str),4-(f1+f2+f3+f4)))