Complex sentence: The first line is "O Harry, thou hast robbed me of my youth!", and the second, cut off in mid-sentence by his death and completed by Prince Hal, is "O Percy, thou art dust, and food for -".
Split into simpler sentences: The first line is "O Harry, thou hast robbed me of my youth!". The second, cut off in mid-sentence by his death and completed by Prince Hal, is "O Percy, thou art dust, and food for -".