1C R+poonceonces
2
3{}
4
5P0(int *x, int *y)
6{
7	WRITE_ONCE(*x, 1);
8	WRITE_ONCE(*y, 1);
9}
10
11P1(int *x, int *y)
12{
13	int r0;
14
15	WRITE_ONCE(*y, 2);
16	r0 = READ_ONCE(*x);
17}
18
19exists (y=2 /\ 1:r0=0)
20