Who Came First Chicken or Egg ?

We often use to ask a question from each others that who came first ? Chicken or Egg ? As this was a quite complicated thing and people often gets confused because hen lay eggs and then they hatch.
But hen itself is hatched from eggs so how could one decide who came first ?

This query has been solved now scientifically,scientists have done many experiments and proved that the protein which composes the egg shell can only be created by hen. So hen came first in the world and after that reproduction process started.