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  1. /**
  2. * Created by iyasuwatts on 10/17/17.
  3. */
  4. import java.util.Scanner;
  5. public class Main {
  6. public static void main(String[] args){
  7. Scanner scanner = new Scanner(System.in);
  8. int userInput = scanner.nextInt();
  9. int answer = 0;
  10. for(int i = 1;i <= userInput; i++) {
  11. answer += i;
  12. }
  13. System.out.println(answer);
  14. }
  15. }