#!/bin/python3

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
    l = [False]*4
    for i in password:
        if(i in numbers):
            l[0] = True
        elif i in lower_case:
            l[1] = True
        elif i in upper_case:
            l[2] = True
        elif i in special_characters:
            l[3] = True
    count = l.count(True)
    if(count == 4 and len(password) >= 6):
        return(0)
    elif(count ==4 and len(password) < 6):
        return(6-len(password))
    elif (count < 4 ):
        additions = 4-count
        if(len(password) + additions >=6):
            return(additions)
        else:
            temp = len(password) + additions
            return(6-len(password))
        
        '''if(len(password) >= 6):
            return(4-count)
        else:
            
            if(additions + len(password) < 6):
                return(6-len(password))
            else:
                return( 6-len(password)-additions)'''

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