text: void printf();
  void* malloc();
  void swap(int* a, int* b) {
    int t = *a;
    *a = *b;
    *b = t;
  }
  int main() {
    int a = 123;
    int b = 321;
    swap(&a, &b);
    printf("%d %d\n", a, b);
    int** c = malloc(2 * sizeof(int*));
    c[0] = malloc(2 * sizeof(int));
    c[1] = malloc(2 * sizeof(int));
    **c = 456;
    *c[1] = 789;
    c[0][1] = 1;
    *(*(c + 1) + 1) = 1;
    printf("%d %d %d %d\n", c[0][0], c[0][1], c[1][0], c[1][1]);
    return 0;
  }
  