sumFirstNaturalNum.java

import java.util.*;

public class sumFirstNaturalNum {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number:");
        int num = sc.nextInt();
        int sum = 0;
        for (int i = 0; i <= num; i++) {
            sum = sum + i;
        }
        System.err.println("Sum of " + num + " Natural numbers:" + sum);
    }
}