#!/bin/python3

import sys

def minimumNumber(n, password):
    a = "0123456789"
    b = "abcdefghijklmnopqrstuvwxyz"
    c = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    d = "!@#$%^&*()-+"
    count1 = count2 = count3 = count4 = 0
    for i in range (n):
        if password[i] in a:
            count1 = 1
        elif password[i] in b:
            count2 = 1
        elif password[i] in c:
            count3 =1
        elif password[i] in d:
            count4 =1
    sum1 = count1 + count2 + count3 + count4
    if n<6:
        if sum1 == 4:
            return 6-n
        else:
            return max(4-sum1,6-n)
            
    else:
        return 4-sum1
            
            
            
       
        
    
    # Return the minimum number of characters to make the password strong

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