using System;

public class Program

{

    public static void Main()

    {

    if(!IfDecreasingPossible(new int[]{1,2,3,4,5}) 

      && IfDecreasingPossible(new int[]{5,4,1,2,1}) 

      && IfDecreasingPossible(new int[]{0,0,-2,-4,-5}) 

      && IfDecreasingPossible(new int[]{7,4,5,-2,-5}))

        {

            Console.WriteLine("all testcases passed");

        }

        Console.WriteLine(IfDecreasingPossible(new int[]{0,-1,-3,-5}));

}

    public static bool IfDecreasingPossible(int[] arr)

    {

        bool isOneRemoved =false;

        bool result =true;

        for(int i=0;i<arr.Length-1;i++)

        {

            if(arr[i]<arr[i+1]) //reverse

            {

                if(isOneRemoved)

                {

                    result =false;

                    break;

                }

                else

                {

                    isOneRemoved=true;

                    if(i!=0 && i<arr.Length-2 )

                    {   if(arr[i-1]>arr[i+1] || arr[i]>arr[i+2])

                        {

                            continue;

                        }

                        else

                        {   result=false;

                        }

                    }

​

                }

            }

        }

        return result;

    }

}