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