Integral inequality with sines

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I am trying to show that there exists some constant $\mathcal{C}>0$ such that: $$\mathcal{C}\leq \int_0^1 |\sin (2\pi n x)-\sin (2\pi m x)|\;dx$$ For all distinct $m,n\in\mathbb{N}$. The constant appears to be a little above $4/5$. I have the feeling I am lacking knowledge of a certain integral inequality though. Maybe knowledge of the constant would shed light on how to proceed. Any ideas would be appreciated.

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An Idea: If you put $$A=\frac{1}{2}|\sin(2\pi nx)-\sin(2\pi mx)|$$ then you have $0\leq A\leq 1$. Hence $A\geq A^2$, and you can integrate $\displaystyle \int_0^1 A^2dx$. (I have not done the computations)