O1=(int **)malloc(3*sizeof(int*));   assert(O1!=NULL);

for (i=0; i<3; i++)

{

            O1[i]=(int *)malloc(2*sizeof(int));    assert(O1[i]!=NULL);

            for (j=0; j<2; j++)

            {

                        O1[i][j]=(int)malloc(3*sizeof(int));    assert(O1[i][j]!=NULL);

            }

}