A man can row a boat in still water at 3km/h. He can walk at a speed of 5km/h on the shore.?

The water in the river flows at 2km/h. If a man rows across the river and walks along the shore to reach the opposite point on the river bank find the direction with the river flow in which he should row so that he could reach the opposite shore in the least possible time. The width of the river is 500m.