View Code of Problem 30

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner=new Scanner(System.in);
		while(scanner.hasNext()) {
			int n=scanner.nextInt();
			long ans=0;
			for(int i=1;i<=n;i++) {
				ans+=i;
			}
			System.out.println(ans);
		}
	}

}