#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special = "!@#$%^&*()-+"
    hasno=0
    lo=0
    up=0
    sp=0
    for i in password:
        if(i in numbers):
            hasno=1
        elif i in lower_case:
            lo = 1
        elif i in upper_case:
            up = 1
        elif i in special:
            sp = 1
    cnt = lo+hasno+up+sp
    if(cnt == 4):
        if(n<6):
            return 6-n
        return 0
    if n>6:
        return 4-cnt
    #if(n+cnt-4 <6):
        #return 6
    if(6-n > 4-cnt):
        return 6-n
    return 4-cnt
    
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)