class Solution {
    public String addBinary(String a, String b) {

        if(a==null||a.length()==0)
            return b;

        if(b==null||b.length()==0)
            return a;

        StringBuilder stb=new StringBuilder();

        int i=a.length()-1;
        int j=b.length()-1;

        int c=0;
        while(i>=0||j>=0){
            if(i>=0)
                c+=a.charAt(i--)-'0';

            if(j>=0)
                c+=b.charAt(j--)-'0';

            stb.append(c%2);
            
            c>>=1;
        }


        String res=stb.reverse().toString();

        return c>0 ? '1'+res:res;

    }
}

public class HelloWorld {
    public static void main(String []args) {
       System.out.println("Hello World!");
		
		String res=addBinary("110010011","11");
		
		System.out.println(res);
    }
	
	static String addBinary(String a, String b) {

        if(a==null||a.length()==0)
            return b;

        if(b==null||b.length()==0)
            return a;

        StringBuilder stb=new StringBuilder();

        int i=a.length()-1;
        int j=b.length()-1;

        int c=0;
        while(i>=0||j>=0){
            if(i>=0)
                c+=a.charAt(i--)-'0';

            if(j>=0)
                c+=b.charAt(j--)-'0';

            stb.append(c%2);
			System.out.println(stb.reverse());
			
            System.out.print(c+" ");
            c>>=1;
            System.out.println(c);
			
			System.out.println();
        }


        String res=stb.reverse().toString();

        return c>0 ? '1'+res:res;

    }
}