program A3Q1

implicit none

integer,parameter :: seed = 837245, p= 521, q=168, nsteps=20
integer, parameter :: M=nsteps+p
integer, dimension(M) :: randseq
integer :: x
integer :: i, j, n, indn,indp,indq, nsamples
integer, dimension(-nsteps:nsteps) :: pos

    i=irand(seed)

    do i=1,p
        randseq(i)=irand()
    enddo 

!  just for fun, generate p more randon numbers and replace
!  original sequence
    do n=p+1, M

        randseq(n) = 1 !here goes the algorith,
        !print *, n, randseq(n)
    enddo

    nsamples=1
    n=p+1
    pos = 0
    !Random walk
    do j=1,nsamples
      x=0
      do i=1, nsteps
        if(.true.)then
! move right
            x=1
        else
!move left
            x=1
        endif
        n=n+1
      enddo !i
!     accumulate histogram in pos
      pos(x) = pos(x) +1 
    enddo !j

    call flush()
end program