Now it works! I'm happy :)
Thank you. Good kata for me.

Oh, I misunderstanded. Sorry.
I tryed it. But still failed.

example

testing(4, 8, 268745, 269161, [
[268793, 268801], [268820, 268828], [268917, 268925], [268962, 268970], 
[268964, 268972], [268990, 268998], [269012, 269020], [269038, 269046], 
[269042, 269050], [269070, 269078], [269110, 269118], [269118, 269126], 
[269122, 269130], [269132, 269140], [269157, 269165] ])

Thanks for your fast reply.
I'm newby of codewars. So could you tell me which document should I read for trying it?

(Elixir)

I got failed message at random test,

testing(3, 10, 214945, 215395, [
[214971, 214981], [215026, 215036], [215035, 215045], [215037, 215047],
[215039, 215049], [215049, 215059], [215092, 215102], [215098, 215108],
[215105, 215115], [215122, 215132], [215155, 215165], [215159, 215169],
[215164, 215174], [215171, 215181], [215195, 215205], [215199, 215209],
[215201, 215211], [215233, 215243], [215237, 215247], [215243, 215253],
[215266, 215276], [215267, 215277], [215291, 215301], [215314, 215324],
[215327, 215337], [215339, 215349], [215395, 215405] ])

Is this test correct?
Last element of expected list, [215395, 215405]'s 2nd element is larger than testing 4th argument(215395).