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

n = int(input())
pw = input()

cont = [1, 1, 1, 1]
for c in pw:
    if numbers.find(c) != -1:
        cont[0] = 0
    elif lower_case.find(c) != -1:
        cont[1] = 0
    elif upper_case.find(c) != -1:
        cont[2] = 0
    elif special_characters.find(c) != -1:
        cont[3] = 0
        
qtd = 0
for x in cont:
    if x == 1:
        qtd += 1
        
print (max(6 - len(pw), qtd))