parameter (n=2097152)
      common a(n), b(n), c(n), d(n)
      open(unit=9, file = 'membank.dat', status='unknown')
      do k = 1,256
         call second(t1)
         do j = 1,64
            do i = k, 64*k, k
               a(i) = b(i) + c(i) + d(i)
            enddo
         enddo
         call second(t2)
         print*, a(i)
         write(9,*)k, t2-t1
      enddo
      do kk = 2,8
         k = kk * 256
         call second(t1)
         do j = 1,64
            do i = k, 64*k, k
               a(i) = b(i) + c(i) + d(i)
            enddo
         enddo
         call second(t2)
         print*, a(i)
         write(9,*)k, t2-t1
      enddo
      close(unit=9)
      stop
      end