s=input()
o=s.count('1')
z=s.count('0')
print(2*min(o,z)) s=input() s input() input o=s.count('1') o s.count('1') s.count s count '1' z=s.count('0') z s.count('0') s.count s count '0' print(2*min(o,z)) print 2*min(o,z) 2 min(o,z) min o z o=s.count('1') s.count('1') o z=s.count('0') s.count('0') z s=input() input() s
s=input()
o=s.count('1')
z=s.count('0')
print(2*min(o,z))