Sum of the First N Numbers

/*
 * Problem : Find the sum 1 + 2 + ... + n.
 * Input   : One integer n (n >= 0).
 * Output  : The sum.
 * Approach: Add the numbers in a loop.
 * Time    : O(n)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int n = new Scanner(System.in).nextInt();

        // Step 1: The sum starts at 0. We use long, because the sum can be larger than an int.
        long sum = 0;

        // Step 2: Visit every number from 1 to n and add it to the sum.
        for (int number = 1; number <= n; number++) {
            sum = sum + number;
        }

        // Step 3: Print the sum.
        System.out.println(sum);
    }
}