C SB+poonceonces

{}

P0(int *x, int *y)
{
	int r0;

	WRITE_ONCE(*x, 1);
	r0 = READ_ONCE(*y);
}

P1(int *x, int *y)
{
	int r0;

	WRITE_ONCE(*y, 1);
	r0 = READ_ONCE(*x);
}

exists (0:r0=0 /\ 1:r0=0)