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.

Example input: Rope and its Usage
Example output: Rope
Example explanation: The word 'Rope' is the key subject here, while Usage is a property of Rope.
Q: Four-stranded (rot-proofed manila or sisal) rope, laid up round a heart or centre made of the same material, is known as shroud-laid rope.
A:
Four-stranded (rot-proofed manila or sisal) rope