s = input()
x = s.count("0")
print(2 * min(x, len(s) - x)) s = input() s input() input x = s.count("0") x s.count("0") s.count s count "0" print(2 * min(x, len(s) - x)) print 2 * min(x, len(s) - x) 2 min(x, len(s) - x) min x len(s) - x len(s) len s x x = s.count("0") s.count("0") x s = input() input() s
s = input()
x = s.count("0")
print(2 * min(x, len(s) - x))