Making lists symmetrical by merging elements
It is better to read input and output files using the with keyword because:


  It is good practice to use the with keyword when dealing with file
  objects. This has the advantage that the file is properly closed after
  its suite finishes, even if an exception is raised on the way. It is
  also much shorter than writing equivalent try-finally blocks:


with open('farmin.txt', 'r') as input:
    # Process the code you need here.