buckets

        // IT JUST WORKS ...//
import java.util.*;
import java.io.*;
import java.math.*;
class Solution {

    public static void main(String args[])
    {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int d = in.nextInt();
        int s = in.nextInt();
        int t = 0;
        int max = n%2==0?n/2:n/2+1;
        for(int i = 1; i <= max; i++)
        {
            t = t + (n/2)*d*s;
        }

        System.out.println(t);
    }
}