# Nicole Kim, 2/5/2019, edited on 2/3/2021
import re

'''In Q40-42, An Othello board is any string of length 64 made up of only the characters in "xX.Oo".  
An Othello edge is any string of length 8 made up of only the characters in "xX.Oo".'''

def num_40(subject):
   # Write a regular expression that will match on an Othello board represented as a string. 
   pattern = "^[xo.]{64}$"   #notice that python does not want / /
   match = re.match(pattern, subject, re.I)
   print (match.group(0)) if match != None else print (match)

def num_41(subject):
   # Given a string of length 8, determine whether it could represent an Othello edge with exactly one hole.
   pattern = "[xo]*\.[xo]*"
   match = re.match(pattern, subject, re.I)
   print (match.group(0)) if match != None else print (match)

def num_42(subject):
   # Given an Othello edge as a string, determine whether there is a hole such that if X plays to the hole (assuming it could), 
   # it will be connected to one of the corners through X tokens. Specifically, this means that one of the ends must be a hole, 
   # or starting from an end there is a sequence of at least one x followed immediately by a sequence (possibly empty) of o, 
   # immediately followed by a hole.
   pattern = "^\.[o]|[o]\.$"
   match = re.search(pattern, subject, re.I)
   print (match.group(0)) if match != None else print (match)

def num_43(subject):
   # Match on all strings of odd length.
   pattern = "/^(..)*.$/"
   match = re.match(pattern, subject, re.DOTALL)
   print (match.group(0)) if match != None else print (match)

def num_44(subject):
   # Match on all odd length binary strings starting with 0, and on even length binary strings starting with 1.
   pattern = ""
   match = re.match(pattern, subject)
   print (match.group(0)) if match != None else print (match)

def num_45(subject):
   # Match all words having two adjacent vowels that differ.
   pattern = ""
   matches = re.finditer(pattern, subject, re.I)
   print ([m.group() for m in matches])

def num_46(subject):
   # Match on all binary strings which DO NOT contain the substring 110.
   pattern = ""
   match = re.match(pattern, subject)
   print (match.group(0)) if match != None else print (match)

def num_47(subject):
   # Match on all non-empty strings over the alphabet {a, b, c} that contain at most one a.
   pattern = ""
   match = re.match(pattern, subject)
   print (match.group(0)) if match != None else print (match)

def num_48(subject):
   # Match on all non-empty strings over the alphabet {a, b, c} that contain an even number of a's.
   pattern = "^[bc]*(a[bc]*a[bc]*)+$"
   match = re.match(pattern, subject)
   print (match.group(0)) if match != None else print (match)

def num_49(subject):
   # Match on all positive, even, base 3 integer strings. 
   pattern = ""
   match = re.match(pattern, subject)
   print (match.group(0)) if match != None else print (match)

while(True):
   input_num = input("Choose the exercise # (40 - 49 or -1 to terminate):")
   if input_num == '-1': exit("Good bye")
   input_str = input("Input string: ")
   eval("num_"+input_num)(input_str)
   print()