Q8393.java

package forRank;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Q8393 {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		int n = Integer.parseInt(br.readLine());
		int sum = 0;
		
		for (int i = 1; i <= n; i++)
			sum += i;
		
		bw.write(sum + "\n");
		
		br.close();
		bw.close();
	}
}