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 Input:
A rogue's yarn is also used in commercially manufactured rope to indicate the type of fibre, its quality, and perhaps the particular manufacturer.

Ex Output:
A rogue's yarn

Ex Input:
Rot-proofing was discontinued in 1963, because rot-proofed cordage has deteriorated in hot and humid conditions.

Ex Output:
Rot-proofing

Ex Input:
The ropes supplied to the Royal Navy are made from various kinds of vegetable fibre which may differ in strength, weight, flexibility, hardness or resistance to wear, elasticity, resistance to weather, or behaviour when wet.

Ex Output:
The ropes