import java.util.Scanner;
import java.util.Arrays;
import java.math.BigDecimal;

public class a{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
		long  a=sc.nextLong();
		long  b=sc.nextLong();
		long  c=sc.nextLong();
		
		double  node;
		
		node = (((double)a/5) * b)/c;
		
		System.out.println(node);
    }
}