s = input()
l = list(s)

a = l.count('0')
b = l.count('1')

ans = 2 * min(a, b)
print(ans) s = input() s input() input l = list(s) l list(s) list s a = l.count('0') a l.count('0') l.count l count '0' b = l.count('1') b l.count('1') l.count l count '1' ans = 2 * min(a, b) ans 2 * min(a, b) 2 min(a, b) min a b print(ans) print ans a = l.count('0') l.count('0') a ans = 2 * min(a, b) 2 * min(a, b) ans s = input() input() s l = list(s) list(s) l b = l.count('1') l.count('1') b
s = input()
l = list(s)

a = l.count('0')
b = l.count('1')

ans = 2 * min(a, b)
print(ans)