1. 
package contestVolumes.volume104;

import java.util.Scanner;

/**
 * FWP, Ausgewählte Probleme aus dem ACM Programming Contest, SS10 
 * Problem: 10491 - Cows and Cars
 * Link: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=16&page=show_problem&problem=1432
 * 
 * @author Siegfried Ippisch
 * @version 1.0
 * 
 * Method : -
 * Status : Accepted
 * Runtime: 1.872
 */
public class CowsAndCars {
	
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		
		while(in.hasNext()){
			System.out.printf("%.5f\n",probabilityOfWinning(in.nextInt(),in.nextInt(),in.nextInt()));
		}
		
		in.close();
	}
	
	/**
	 * Idea:
	 * 
	 * Case 1: first chose is a Car (carChance = cars/doors)
	 * -> remainingCars = cars - 1
	 * -> remianingCows = cows - show
	 * -> remainingDoors = doors -1 - show
	 * carWinChance = remainingCars/remainingDoors
	 * 
	 * Case 2: first chose is a Cow (cowChance = cows/doors)
	 * -> remainingCars = cars
	 * -> remianingCows = cows - 1 - show
	 * -> remainingDoors = doors - 1 - show
	 * cowWinChance = remainingCars/remainingDoors
	 * 
	 * total chance to win the car = carChance*carWinChance + cowChance*cowWinChance
	 */
	public static double probabilityOfWinning(double cows, double cars, double show){
		double doors = cars + cows;
		return (cars*(cars-1 + cows))/
				(doors*(doors-1-show));
	}
	
}