main()
{
        int i = 10;
        const ci = 20;
        int *pi = &i;
        const int *pci = &ci;
        int * const cpi = &i;
        const int * const cpci = &ci;

        pi = &i;        /* OK */
        *pi = 20;       /* OK */
/*1*/   pi = &ci;       /* error */

        pci = &ci;      /* OK */
        *pci = 25;      /* error */
/*2*/   pci = &i;       /* OK */
        *pci = 25;      /* error */

        *cpi = 10;      /* OK */
        cpi = &i;       /* error */

        *cpci = 10;     /* error */
        cpci = &ci;     /* error */
}