What is the minimum positive period of y = (SiNx cosx) ^ 2-1?

What is the minimum positive period of y = (SiNx cosx) ^ 2-1?

y=(sinx-cosx)^2-1
=(sinx)^2-2sinxcosx+(cosx)^2-1
=1-sin2x-1
=-sin2x
T=2π/2=π