백준 #14924번 폰 노이만과 파리

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int s = sc.nextInt();
		int t = sc.nextInt();
		int d = sc.nextInt();
		
		System.out.println(d / (s * 2) * t);
		sc.close();
	}
}