anchor.diff:  
   
       write (*,*) "Perfect numbers"
  -    write (*,*) "==============="
  +    write (*,*) "---------------"
       call system_clock(tic)
       call perfect_numbers(pn_limit, res_pn)
       call system_clock(toc)
  
positive.code: 
  
      write (*,*) "Mandelbrot set"
      write (*,*) "=============="
      call system_clock(tic)
      res_img = create(width, height, -0.5, 0.0, 4.0/width)
      call system_clock(toc)
  
negative.code: program benchmark
  
      use iso_fortran_env, only: compiler_version, compiler_options 
      use omp_lib, only: omp_get_thread_num, omp_get_num_threads
  
      use fibonacci
      use perfect_number
  