View Code of Problem 30

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		while(scanner.hasNext()) {
			int n = scanner.nextInt();
			int sum = 0;
			for(int i = 1;i <= n;i++) {
				sum += i;
			}
			System.out.println(sum);
		}
	}
}