using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[] input = { -3, 26, -2, 19, 2, 19, 3, 29, 1, 48 };

        var result2 = Enumerable.Range(0, input.Length/2)

                          .Select(i => input[i*2] * input[i*2 + 1]).Sum();

        Console.WriteLine(result2);

    }

}