S = input()
x = S.count('0')
y = S.count('1')

ans = 2 * (min(x, y))
print(ans) S = input() S input() input x = S.count('0') x S.count('0') S.count S count '0' y = S.count('1') y S.count('1') S.count S count '1' ans = 2 * (min(x, y)) ans 2 * (min(x, y)) 2 min(x, y) min x y print(ans) print ans ans = 2 * (min(x, y)) 2 * (min(x, y)) ans x = S.count('0') S.count('0') x y = S.count('1') S.count('1') y S = input() input() S
S = input()
x = S.count('0')
y = S.count('1')

ans = 2 * (min(x, y))
print(ans)