#!/bin/python3
numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"
import sys
im1 = 1
im2 = 1
im3 = 1
im4 = 1
minlen = 6
answer = 0
def minimumNumber(n, password):
    global answer
    global im1
    global im2
    global im3
    global im4
    if n < minlen:
        if minlen-n > answer:
            answer = minlen-n
    for i in password:
        if i in numbers:
            im1 = 0
        elif i in lower_case:
            im2 = 0
        elif i in upper_case:
            im3 = 0
        elif i in special_characters:
            im4 =0
    if im1 == 1 or im2 == 1 or im3 == 1 or im4 == 1:
        if im1+im2+im3+im4 > answer:
            answer = im1+im2+im3+im4
    return (answer)

if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)