using System;
/*
 * Write a program that prints the first 1000 members of the sequence: 2, -3, 4, -5, 6, -7, …
 * You might need to learn how to use loops in C# (search in Internet).
 */
class PrintLongSequence
{
    static void Main()
    {
        int i = 2;
        for (int j = 0; j < 1000; j++)
        {
            if (i % 2 == 0)
            {
                Console.Write(i + "\t");
                i++;
                continue;
            }
            Console.Write(-i + "\t");
            i++;
        }
    }
}