/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		java.util.Scanner i = new java.util.Scanner(System.in);
		double t1 = i.nextDouble();
		double t2 = i.nextDouble();
		double t3 = i.nextDouble();
    
    double t;
    t = (t1*t2*t3) / (t1*t2 + t1*t3 + t2*t3);
    if(t1*t2*t3 == 0) System.out.println(t);
        else System.out.printf("%.2f",t);
	}
}