// Suit Distribution
package main

import (
	"fmt"
	"os"
)

func read_distribution(file *os.File) (int, int) {
	var number1, number2 int
	_, err := fmt.Fscanf(file, "%d %d\n", &number1, &number2)

	if err != nil {
		panic(fmt.Sprintf("Scan Failed: %v", err))
	}

	return number1, number2
}

func write_integer(file *os.File, number int) {
	_, err := file.WriteString(fmt.Sprintf("%d\n", number))
	if err != nil {
		fmt.Printf("error writing string: %v", err)
	}
}

func combination(n int, k int) int {
	result := 1
	if k > (n - k) {
		k = n - k
	}
	for i := k + 1; i <= n; i++ {
		result *= i
	}
	for i := 2; i <= n-k; i++ {
		result /= i
	}
	return result
}

func probability(hand1 int, hand2 int) float64 {
	denominator := combination(26, 13)
	numerator := combination(hand1+hand2, hand1)
	numerator *= combination(26-hand1-hand2, 13-hand1)
	result := float64(numerator) / float64(denominator)
	if hand1 != hand2 {
		result *= 2
	}
	return result
}

func main() {
	input_file, err := os.Open("suit.in")
	if err != nil {
		fmt.Println(err)
	}
	defer input_file.Close()

	output_file, err := os.Create("suit.out") // creating...
	if err != nil {
		fmt.Printf("error creating file: %v", err)
		return
	}
	defer output_file.Close()

	cards1, cards2 := read_distribution(input_file)
	for cards1 != -1 && cards2 != -1 {
		result := probability(cards1, cards2)
		// fmt.Printf("%d-%d split: %.8f\n", cards1, cards2, result)
		output_file.WriteString(fmt.Sprintf("%d-%d split: %.8f\n", cards1, cards2, result))
		cards1, cards2 = read_distribution(input_file)
	}
}