In this task, you are given a sentence. You must find the primary subject in the supplied sentence. The output must be a sub-sequence in the sentence.

[EX Q]: The shorter the length of the fibres the harder this twist must be to give the necessary strength to the yarn.
[EX A]: the yarn

[EX Q]: To assist in distinguishing the different types of cordage a coloured jute yarn known as a rogue's yarn is woven into the strands of each type of rope manufactured at the Admiralty Ropery.
[EX A]: the different types of cordage

[EX Q]: Manila hawser-laid rope is supplied to the Royal Navy in coils of 120 fathoms, and it is marked with one red rogue's yarn in each of two strands.
[EX A]:
Manila hawser-laid rope

