public class EncodeBits
{
    public static int decode(long d)
    {
        int res = 0;
        
        for (int i = 0; i < 64; i++) {
            if ((d & (1L << i)) != 0) {
                res ^= i;
            }
        }
        
        return res;
    }

    public static long encode(long random, int val)
    {
        int current = decode(random);
        int change = current ^ val;
        return random ^ (1L << change);
    }
}