#!/bin/python

import sys

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


def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    passlen = len(password)
    hasnum = any(elem in password for elem in numbers)
    haslow = any(elem in password for elem in lower_case)
    hasup = any(elem in password for elem in upper_case)
    hasspec = any(elem in password for elem in special_characters)
    #print hasnum
    
    needed = 0
    if not hasnum:
        needed += 1
    if not haslow:
        needed += 1
    if not hasup:
        needed += 1
    if not hasspec:
        needed += 1

    if passlen + needed < 6:
        return 6-passlen
    else:
        return needed
    

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