#!/bin/python

import sys

def minimumNumber(n, password):
    numbers = set("0123456789")
    lower_case = set("abcdefghijklmnopqrstuvwxyz")
    upper_case = set("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    special_characters = set("!@#$%^&*()-+")
    l=u=s=num=0
    
    p=set(password)
    for i in p:
        if i in numbers:
            num=1
        if i in lower_case:
            l=1
        if i in upper_case:
            u=1
        if i in special_characters:
            s=1
    if n<6:
        l6=6-n
    else:
        l6=0
    c_req= 4-num-l-u-s
    if c_req<=l6:
        return l6
    else:
        return c_req
        
    

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