package main

import (
	"fmt"
	"math"
)

var (
	x, y, r float64
)

func resolve() float64 {
	X := math.Abs(x)
	Y := math.Abs(y)
	return math.Ceil(X + Y + math.Sqrt(2)*r)
}

func main() {
	fmt.Scanf("%f %f %f\n", &x, &y, &r)
	fmt.Println(int(resolve()))
}