#!/bin/python

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    special = 0
    lower = 0
    upper = 0
    digit = 0
    for c in password:
        if c in "!@#$%^&*()-+":
            special = 1
        elif c.islower():
            lower = 1
        elif c.isupper():
            upper = 1
        elif c.isdigit():
            digit = 1
    need = 4 - special - lower - upper - digit
    if (need + n) < 6:
        return 6 - n
    return need
        

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