title: ValueError: invalid literal for int() with base 10:
body: <p>This is a game that asks users to enter a location on a 3 by 3 grid and then another user attempts to guess the location. Having a problem debugging an error.</p>
  
  <p>What is the problem with this line?   <code>Col=int(guess[1:])-1</code></p>
  
  <p>In the following code?</p>
  
  <p>It returns the following error when I try and run it in repl.it.</p>
  
  <blockquote>
    <p>Traceback (most recent call last):   File "python", line 84, in
       File "python", line 71, in <em>init</em> ValueError: invalid
    literal for int() with base 10: ''</p>
  </blockquote>
  
  <pre><code>#Creation of the grid and the user interface list
  grid = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
  turns=0
  guess="x"
  #Function to clear screen
  def cls(): 
    print ("\n" * 100)
  
  #Function to validate coordinate
  def validate_entry():
    valid=False
    while valid==False:
      guess=input("Enter a location from A1 to C3: ")
      loc = guess.upper() #Use upper case
      row = guess[0:1]
      col = guess[1:2]
      if(row!="A" and row!="B" and row!="C") or (col!="1" and col!="2" and col!="3"):
        print("Your location is invalid.")
        print("")
        return False #not actually needed, but helps see what is happening
      else:
       valid=True
       return True
  #Function to set the location of the treasure
  def settingTreasure(grid):
  
      treasureSet=input("Set location by entering a location from A1 to C3: ")
      #Converting the letter into a coordinate in the list
      treasure_letter=str(treasureSet[:1])
      if treasure_letter in ["a", "A"]:
        locRow=0
      elif treasure_letter in ["b", "B"]:
        locRow=1
      elif treasure_letter in ["c", "C"]:
        locRow=2
      #Converting the number into a list coordinate
      locCol=int(treasureSet[1:])-1
      grid[locRow][locCol]=1
  
  settingTreasure(grid)
  cls()
  #Displaying the user interface in a clean manner
  def gameBoard():
    UI = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
    for i in range(0,len(UI)):
      print(UI[i])
  
  gameBoard()
  
  #The main loop that contains the game
  def _init_(turns, guess):
    turns=turns+1
   #If the player exceeds three turns they lose
    if turns&gt;3:
      print("Too many turns! You lose!")
      quit()
  
    #Prints number of turns
    print(" ")
    print("Turn " + str(turns))
    validate_entry()
    #Converting the letter into a coordinate in the list
    guess_letter=str(guess[:1])
    if guess_letter in ["a", "A"]:
      Row=0
    elif guess_letter in ["b", "B"]:
      Row=1
    elif guess_letter in ["c", "C"]:
      Row=2
    #Converting the number into a list coordinate
    Col=int(guess[1:])-1
  
    #Test to see if they guessed treasure location
    if grid[Row][Col]==1:
      print(" ")
      print("found treasure!")
      quit()
    else:
      print(" ")
      print("Treasure not here!")
  
  #Loop for the main game
  while True:
   _init_(turns, guess)
  </code></pre>