#!/bin/python3

import sys

def minimumNumber(n, s):
    # Return the minimum number of characters to make the password strong
    c = 0
    c_l = 0
    c_u = 0
    c_s = 0
    c_n = 0
    l = 'abcdefghijklmnopqrstuvwxyz'
    u = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    n_n = '0123456789'
    sp = '!@#$%^&*()-+'
    for i in range(n):
        if(s[i] in u):
            c_u+=1
        elif(s[i] in l):
            c_l+=1        
        elif(s[i] in n_n):
            c_n+=1
        elif(s[i] in sp):
            c_s+=1
    if(c_l==0):
        c+=1
    if(c_u==0):
        c+=1
    if(c_s==0):
        c+=1
    if(c_n==0):
        c+=1
    if(n<6):
        if(6-n>c):
            return 6-n
    return c

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