In this task, you are given a premise sentence. Your task is to write a new sentence by substituting the subject and object (i.e., the input's subject should be output's object and vice versa.). The generated sentence must be fluent and shouldn't change the voice (i.e., passive or active) of the input.

The artists thanked the president .
The president thanked the artists .

The athletes helped the students that contacted the senator .
The students helped the athletes .

The doctors who the athlete believed stopped the secretaries .

The secretaries stopped the doctors .