#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    special_characters = "!@#$%^&*()-+"
    
    digit = lower = upper = special = 0
    
    for i in range(n):
        a = password[i]
        if digit == 0:
            digit = 1 if a.isdigit() else 0
        if lower == 0:
            lower = 1 if a.islower() else 0
        if upper == 0:
            upper = 1 if a.isupper() else 0
        if special == 0:
            special = 1 if a in special_characters else 0
    
    to_solve = 4 - digit - lower - upper - special
    
    if n >= 6:
        return to_solve
    elif n > 6 - to_solve:
        return to_solve
    else:
        return 6 - n
        
    
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)