#!/bin/python

import sys

number = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"



def minimumNumber(x, password):
    n=0
    l=0
    u=0
    p=0
    for i in password:
        if(i in number):
            n=1
        elif(i in lower_case):
            l=1
        elif(i in upper_case):
            u=1
        elif(i in special_characters):
            p=1 
    ans=4-(n+l+u+p)
    if(ans==0):
        if(len(password)>=6):
            return 0
        else:
            return 6-len(password)
    else:
        if(len(password)>=6):
            return ans
        else:
            return max(6-len(password),ans)
    
    
    

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