import sys
input = sys.stdin.readline

s = list(input().strip())
r = s.count('0')
b = s.count('1')
print(2*min(r,b)) import sys sys input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline s = list(input().strip()) s list(input().strip()) list input().strip() ().strip () input strip r = s.count('0') r s.count('0') s.count s count '0' b = s.count('1') b s.count('1') s.count s count '1' print(2*min(r,b)) print 2*min(r,b) 2 min(r,b) min r b r = s.count('0') s.count('0') r input = sys.stdin.readline sys.stdin.readline input s = list(input().strip()) list(input().strip()) s b = s.count('1') s.count('1') b
import sys
input = sys.stdin.readline

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