package com.javarush.task.pro.task04.task0412;

import java.util.Scanner;

/*
Сумма кратных чисел
*/

public class Solution {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int start = scanner.nextInt();
        int end = scanner.nextInt();
        int multiple = scanner.nextInt();

        int sum = 0;
        for (int i = start; i < end; i++) {
            if (i % multiple == 0)
            {
                sum = sum + start;
            }
        }
        System.out.println(sum);
    }
}