4  people  Ram, Laxman , Bharat Shatrughan  .  Ram takes 1 minute to cross a tunnel. Laxman takes 2 minutes, Bharat takes 5 minutes and Shtrughan takes 10 minutes to cross a tunnel.

Problem with tunnel was there is only place for 2 people to cross at one  time  and it was so dark they need a torch and they had only one torch.

In what order did they cross the tunnel so that all of them cross the tunnel within 17 minutes ?