For any real number x, let [x] denote the largest integer less than or equal to x. Let f be a real valued function defined on the interval [−10,10] by
f(x)={x−[x]1+[x]−xif [x] is oddif [x] is even
Then the value of 10π2∫−1010f(x)cosπxdx is
[JEE 2010]