Populating one array with elements of another array. Exceeding the length of the second array exception

I am trying to take the elements of one array "arr", subtract them one after the other and then populate a second array "newArr" with these values.  For example I have my first array  { 300, 100, -10 } the second array should be {200, 90}

Here is what I got, but it throws an exception that  "Index was outside the bounds of the array."

using System;

class Program
{
    static void Main()
    {
        int value = 0;
        int[] arr = new int[] { 300, 100, -10 };
        int[] newArr = new int[arr.Length];
       
        for (int i = 0; i < arr.Length; i++)
        {
            if (i + 1 < arr.Length)
                    {
                        newArr[value] = arr[i] - arr[i + 1];
                    }
                    value++;
        }
        Console.WriteLine(value);
    }
}
What is wrong with it?