using System;

public class Program

{

    public static void exo1()

    {

        Console.WriteLine("Entrez un nombre");

        int n = Convert.ToInt32(Console.ReadLine());

        for (int i = 1; i < n; i=i+2)

        {

            Console.WriteLine(i);

        }

    }

    public static void exo2()

    {

        Console.WriteLine("Entrez un nombre");

        int n = Convert.ToInt32(Console.ReadLine());

        int somme = 0;

        for (int i = 1; i < n; i++)

        {

            somme = somme + i;

            Console.Write(i);

            Console.Write("   ");

            Console.WriteLine(somme);

        }

    }

    public static void Main()

    {   //exo1();

        exo2();

    }

​

}