#!/bin/python

import sys
import re
def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    
    size = len(password)
    diffSize = 6-size
    num = False
    up=False
    low = False
    sp = False
    
    for x in password:
        if num==False and x in numbers:
            num=True
        if up==False and x in upper_case:
            up=True
        if low==False and x in lower_case:
            low=True
        if sp==False and x in special_characters:
            sp=True
        if num and up and low and sp:
            if size>=6:
                return 0
            break
    dk = 0
    for v in [num,sp,up,low]:
        if v==False:
            dk+=1
    if dk<diffSize:
        return diffSize
    return dk


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