package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)

	var n, m, k int64
	fmt.Fscan(in, &n, &m, &k)

	if n+k < m {
		fmt.Printf("%.10f\n", 0.0)
		return
	}

	if k >= m {
		fmt.Printf("%.10f\n", 1.0)
		return
	}

	d := k + 1
	if d > m {
		fmt.Printf("%.10f\n", 1.0)
		return
	}

	ratio := 1.0
	for i := int64(1); i <= d; i++ {
		ratio *= float64(m-i+1) / float64(n+i)
	}

	ans := 1.0 - ratio
	if ans < 0 {
		ans = 0
	}
	if ans > 1 {
		ans = 1
	}

	fmt.Printf("%.10f\n", ans)
}