def taskOfPairing(freq):
  count = 0
  marker = False
  for i in freq:
    if i != 0:
      count += i // 2
      if i % 2 != 0 and marker:
        count += 1
        marker = False
       elif i % 2 != 0:
        marker = True
    else:
      marker = False
  return count