import java.util.*;enum W{_;System z;String a;{for(Scanner r=new Scanner(z.in);r==r;z.out.println(a))for(a=r.next();a!=(a=a.replaceAll("01|10","").replaceAll("\\{0+}","0").replaceAll("\\{1*}","1")););}}
Note that non-ascii characters in the above source code will be escaped (such as \x9f).