Khairul agrees to lay a road 3000m long in 30 days. He employs 50 men,who works for 8 hours a day .After 20 working days, he finds that only 1200 m of the road is completed. Each man now works for 10 hours a day and they have to finish the project in 10 days' time. So , Khairul decides to employ more men to work on the project. How many more men are to be employed to finish the work on time?