using System;

using System.Linq;

​

public class Program

{

    /*

    Some people are standing in a row in a park. There are trees between them which cannot be moved.

    Your task is to rearrange the people by their heights in a non-descending order without moving the trees.

    Example

    For a = [-1, 150, 190, 170, -1, -1, 160, 180], the output should be

    sortByHeight(a) = [-1, 150, 160, 170, -1, -1, 180, 190].

    */

​

    static void sortByHeight(int[] a)

    {

        // fill in

    }

​

    public static void Main()

    {

        var a = new int[] { -1, 150, 190, 170, -1, -1, 160, 180 } ;

        sortByHeight(a);

        Console.WriteLine(String.Join(", ", a.Select(v => v.ToString())));

    }

}