Geo-gebra 3

An isosceles right triangle $OBC$ , $O$ is the right angle and the hypotenuse $BC = \sqrt 2$ . Inside the triangle there are two similar circular arcs of radius 1 with centres at $C$ and $B$ , and they intersect at $O$ and cut the hypotenuse at the points $D$ and $E$ . If the blue area $ODE$ is $A$ , then $4A = \pi - a$ , where $a$ is a positive integer. Find $a$ .