백준알고리즘 8393번 java

import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();
        int sum=0;
        if(n>0 && n<10001)
            for(int i=0; i<n+1; i++){
                sum+=i;
            }
        System.out.print(sum);
    }
}