Elastic and inelastic collisions

Two identical smooth trolleys, each of mass $0.50\,\text{kg}$, move towards each other on a straight track. One has speed $0.80\,\text{m s}^{-1}$ to the right, the other $0.80\,\text{m s}^{-1}$ to the left. They collide head-on elastically. What is the total kinetic energy of the two trolleys after the collision?