Trigonometric Functions And Equations

Let \({S_1} = \{ x \in [0,12\pi ]:{\sin ^5}x + {\cos ^5}x = 1\}\)

and \({S_2} = \{ x \in [0,8\pi ]:{\sin ^7}x + {\cos ^7}x = 1\}\)

Then \(n({S_1}) - n({S_2})\) is equal to ______________.