char **Expand_maze_row(char **maze, int nrow, int ncol, int *rrow, int *rcol)
{
   *rrow = *rcol = 0;
   char ** new_maze;
   int new_nrow = 2*nrow -1;
   printf("address of maze = %p\n",maze);
   new_maze = (char**)realloc(maze,new_nrow*ncol*sizeof(char*));
   printf("address of new_maze = %p\n",new_maze);
   new_maze[0] = (char*)malloc(new_nrow*ncol*sizeof(char));
   if(new_maze == NULL|| new_maze[0] == NULL)
     {
       *rrow = *rcol = 0;
       free(new_maze);
       return NULL;
     }
   else{
     int i,j;
     maze = new_maze;
     //assign address
     for(i = nrow; i<new_nrow;i++){
       maze[i] = &(maze[0][i*ncol]);
     }
     //test
     printf("address of maze = %p\n",maze);
     for(i = 0; i<(new_nrow); i++){
       printf("row# = %d\n",i);
       for(j = 0;j<ncol;j++){
	 maze[i][j] = i+1;
	 printf("%d ",maze[i][j]);
       }
       printf("\n");
     }
     printf("wtf");
     *rrow = new_nrow;
     *rcol = ncol;
     return new_maze;
   }
}