count serial numbers with even numbers apearing negative, while odd appears positive

postiveOddNegativeEven.cs

using System;

public class PositiveOddNegativeEven{

  public static void Main(){
  
  for(int i=0; i<20; i++){
          if(i%2==0){
          Console.WriteLine(i);
          }else{
          Console.WriteLine("-"+i);
          }
  
      }
  }

}