recursive function qsort(x) result(y)
  integer,intent(in) ::x(:)
  integer,allocatable::y(:)
  integer::pivot,total
  total = size(x)
  if (total <=1) then
     y = x
  else
     pivot = x(total/2)
     y = [qsort(pack(x, x .lt. pivot)), &
          pack(x, x .eq. pivot),        &
          qsort(pack(x, x .gt. pivot))]
  endif
end function qsort

program main
  interface
     recursive function qsort(x) result(y)
       integer,intent(in) ::x(:)
       integer,allocatable::y(:)
     end function qsort
  end interface
  integer,parameter::initdist=1000001
  integer::N,i,mindist=initdist
  integer,allocatable::X(:)
  integer,allocatable::Y(:)
  read *,N
  allocate(X(N))
  allocate(Y(N))
  read *,X
  Y=qsort(X)
  do i=1,N-1
     if(Y(i).eq.Y(i+1)) cycle
     mindist = MIN(mindist, Y(i+1)-Y(i))
     if(mindist.eq.1) exit
  end do
  if(mindist.eq.initdist) mindist=0
  print '(i0)', mindist
end program main