public static long sumXor(long n) {
        // Write your code here
        if(n == 0) return 1 ;
        
        int totalOneBits = Long.bitCount(n) ;
        int totalBits = Long.toBinaryString(n).length() ;
         int zeroBits = totalBits - totalOneBits ;
         
         return 1l << zeroBits ; //bitwise left shift => 8 4 2 1 ;power of 2
    }