#!/bin/python

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    l=list(password)
    numbers = list("0123456789")
    lower_case = list("abcdefghijklmnopqrstuvwxyz")
    upper_case = list("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    special_characters = list("!@#$%^&*()-+")
    c1=0
    c2=0
    c3=0
    c4=0
    for i in l:
        if(i in numbers):
            c1+=1
        elif(i in lower_case):
            c2+=1
        elif(i in upper_case):
            c3+=1
        elif(i in special_characters):
            c4+=1
    c=0
    if(c1>0 and c2>0 and c3>0 and c4>0 and len(l)>=6):
        return 0
    
    else:
        if(c1==0):c+=1
        if(c2==0):c+=1
        if(c3==0):c+=1
        if(c4==0):c+=1
    if(len(l)>=6):
        return c
    else:
        if(c>6-len(l)):
            return c
        else:
            return 6-len(l)
        
            
                    

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