How much more shares acquired on vesting did Gregory S. Clark have over  Nicholas R. Noviello?
{"Gregory S. Clark": {"Number of Shares Acquired on Exercise (#)": "\u2014", "Value Realized on Exercise (1)($)$)": "\u2014", "Number of Shares Acquired on Vesting(2) (#)": 342338, "Value Realized on Vesting (3)($)$)": 7467791}, "Nicholas R. Noviello": {"Number of Shares Acquired on Exercise (#)": 332155, "Value Realized on Exercise (1)($)$)": 4699993, "Number of Shares Acquired on Vesting(2) (#)": 111855, "Value Realized on Vesting (3)($)$)": 2419818}, "Amy L. Cappellanti-Wolf": {"Number of Shares Acquired on Exercise (#)": "\u2014", "Value Realized on Exercise (1)($)$)": "\u2014", "Number of Shares Acquired on Vesting(2) (#)": 92644, "Value Realized on Vesting (3)($)$)": 1997239}, "Samir Kapuria": {"Number of Shares Acquired on Exercise (#)": "\u2014", "Value Realized on Exercise (1)($)$)": "\u2014", "Number of Shares Acquired on Vesting(2) (#)": 112125, "Value Realized on Vesting (3)($)$)": 2497640}, "Scott C. Taylor": {"Number of Shares Acquired on Exercise (#)": "\u2014", "Value Realized on Exercise (1)($)$)": "\u2014", "Number of Shares Acquired on Vesting(2) (#)": 103798, "Value Realized on Vesting (3)($)$)": 2216595}}
shares_clark = df["Gregory S. Clark"]["Number of Shares Acquired on Vesting(2) (#)"]
shares_noviello = df["Nicholas R. Noviello"]["Number of Shares Acquired on Vesting(2) (#)"]
answer = shares_clark - shares_noviello