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

Example Input: Handling of man-made fibre cordage.
Example Output: man-made fibre cordage

Example Input: Construction and types.
Example Output:
Construction