scc

 1struct node {
 2	int index;
 3};
 4
 5struct node nodes[2];
 6
 7int
 8main(void)
 9{
10	int d = 1, c;
11
12	d = 1;
13	c = nodes[--d].index++;
14	if (d != 0 || nodes[0].index != 1)
15		return 1;
16
17	d = -1;
18	c = nodes[++d].index--;
19	if (d != 0 || nodes[0].index != 0)
20		return 2;
21
22	return 0;
23}