using System;
using System.Runtime.InteropServices;

namespace MyTestProg{
    class Program{

        [DllImport("MyProjectLibrary.dll")]
        private static extern int OnePlus(int input_var);

        static void Main(string[] args){
            int i=1;
            i = OnePlus(i);
            Console.WriteLine("Hello world! %d",i);
        }
    }
}