You are in Manhattan and need to walk from point A to point B$.$ The person you are with suggests that you will get there quicker if you walk directly towards your destination. Given that buildings are in the way, the most "direct" route results in zig$-$zagging as shown in the figure, since you are only able to travel exactly east or exactly north. Consider the figure and compare the yellow zig$-$zag path with the blue$-$green single$-$turn path.