// No.172 UFOを捕まえろ
package main

import (
	"fmt"
	"math"
)

func abs(a int) int {
	if a >= 0 {
		return a
	} else {
		return -a
	}
}

func main() {
	var x, y, r int
	fmt.Scan(&x, &y, &r)

	a := math.Sqrt(float64(r * r / 2))
	m := abs(x) + abs(y) + int(math.Ceil(2*a))
	fmt.Println(m)
}