Java 代码

import java.util.Scanner;

public class Main
{   
    public static int sum(int l, int r)
    {
        int sum = 0;
        for (int i = l; i <= r; i ++)
            sum += i;
        return sum;
    }

    public static void main(String[] args)
    {
        Scanner cin = new Scanner(System.in);

        int m = cin.nextInt();
        int n = cin.nextInt();

        System.out.println (sum (m, n));
    }
}