[java] 8393.합구하기

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        //StringTokenizer st = new StringTokenizer(br.readLine());

        int t = Integer.parseInt(br.readLine());
        int sum = 0;

        for (int i=0;i<=t;i++) {
            sum = sum + i;
        }

        System.out.println(sum);

        //int a = Integer.parseInt(br.readLine());

    }
}