[SoftUni Java] ExamPreparation 02.Tribonacci

import java.math.BigInteger;
import java.util.Scanner;
public class Program {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        long t1 = input.nextLong();
        BigInteger first = BigInteger.valueOf(t1);
        long t2 = input.nextLong();
        BigInteger second = BigInteger.valueOf(t2);
        long t3 = input.nextLong();
        BigInteger third = BigInteger.valueOf(t3);

        BigInteger next = BigInteger.valueOf(0);

        int n = input.nextInt();

        if (n == 1) {
            System.out.println(t1);
        }
        else if (n == 2) {
            System.out.println(t2);
        }
        else if (n== 3) {
            System.out.println(t3);
        }
        else {
            for (int i = 4; i <= n; i++) {
                next = next.add(first);
                next = next.add(second);
                next = next.add(third);

                first = BigInteger.valueOf(0);
                first = first.add(second);

                second = BigInteger.valueOf(0);
                second = second.add(third);

                third = BigInteger.valueOf(0);
                third = third.add(next);

                next = BigInteger.valueOf(0);
            }
            System.out.println(third);
        }
    }

}