program main
  implicit none
  integer::N,i,m
  integer,allocatable::a(:)
  read *,N
  allocate(a(N))
  read *,a(1:N)
  m = N
  do i=N,1,-1
     if(a(i).eq.m) then
        m = m - 1
     end if
  end do
  print '(i0)', m
end program main