#!/bin/python

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"

    countn=0
    for i in range(10):
        for j in range(len(password)):
            if(password[j]==numbers[i]):
                    countn=countn+1
    
    countl=0
    for k in range(26):
        for l in range(len(password)):
            if(password[l]==lower_case[k]):
                    countl=countl+1
    countu=0
    for m in range(26):
        for q in range(len(password)):
            if(password[q]==upper_case[m]):
                    countu=countu+1
    countc=0
    for o in range(12):
        for p in range(len(password)):
            if(password[p]==special_characters[o]):
                    countc=countc+1
    soln=0
    if(countn==0):
        soln=soln+1
    if(countl==0):
        soln=soln+1
    if(countu==0):
        soln=soln+1
    if(countc==0):
        soln=soln+1
    
    if(n>=6):
        return soln
    if(n<6):
        if(soln>6-n):
            return soln 
        else:
            return 6-n 
   
            
 

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