static int[] Assigning ()
        {
            // Initialization.
            int f = 0, s = 0;
            int[] resArr = new int[101];

            // Logic.
            for(int i = 0; i < resArr.Length; i++)
            {
                if (f == 0)
                {
                    f = i + 1;
                    resArr[i] = f;
                    s = 0;
                }
                else if(s == 0)
                {
                    s = i + 1;
                    resArr[i] = s;
                    f = 0;
                }
            }

            // Output.
            return resArr;
        }