Tribonacci to solve 50/100

package JavaSample;

import java.util.Scanner;

public class Tribonacci {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        long t1 = scan.nextLong();
        long t2 = scan.nextLong();
        long t3 = scan.nextLong();
        long n = scan.nextLong();
        long sum = 0;

        if (n == 1) {
            sum = t1;
        } else if (n == 2) {
            sum = t2;
        } else if (n == 3) {
            sum = t3;
        }
        else {
        for (int i = 3; i < n; i++) {

            sum = t1 + t2 + t3;
            t1 = t2;
            t2 = t3;
            t3 = sum;
        }
        }
        System.out.println(sum);
    }

}