s = input()
num = s.count('0')
print(2 * min(num, len(s) - num)) s = input() s input() input num = s.count('0') num s.count('0') s.count s count '0' print(2 * min(num, len(s) - num)) print 2 * min(num, len(s) - num) 2 min(num, len(s) - num) min num len(s) - num len(s) len s num num = s.count('0') s.count('0') num s = input() input() s
s = input()
num = s.count('0')
print(2 * min(num, len(s) - num))