#!/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
    t1 = 0
    t2 = 0
    t3 = 0
    t4 = 0
    for c in password:
        if c in numbers:
            t1 = 1
        if c in lower_case:
            t2 = 1
        if c in upper_case:
            t3 = 1
        if c in special_characters:
            t4 = 1
    rs = 4 - (t1 + t2 + t3 + t4)
    if n < 6:
        return max(rs, 6 - n)
    else:
        return rs
      

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