Tribonacci Nth Element

using System;
class TribonacciNthElement
{
  static void Main()
  {
    //Telerik Academy
    //The Tribonacci sequence is a sequence in which every next element is made by the sum of the previous three elements from the sequence.
    //Write a computer program that finds the Nth element of the Tribonacci sequence, if you are given the first three elements of the sequence and the number N. Mathematically said: with given T1, T2 and T3 – you must find Tn.

    int smallest = int.Parse(Console.ReadLine());
    int middle = int.Parse(Console.ReadLine());
    int biggest = int.Parse(Console.ReadLine());
    int n = int.Parse(Console.ReadLine());

    for (int i = 4; i <= n; i++)
    {
      int next = smallest + middle + biggest;
      smallest = middle;
      middle = biggest;
      biggest = next;
    }
    Console.WriteLine(biggest);
  }
}