if (fork() == 0) { a = a + 5; printf(“%d, %d\n”, a, &a);
}
else {
a = a – 5; printf(“%d, %d\n”, a, &a);
u = x + 10 且 v = y
u = x + 10 且 v != y
u + 10 = x 且 v = y
u + 10 = x 且 v != y
