// No.172 UFOを捕まえろ
package main

import (
	"fmt"
)

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)

	aa := 1
	for aa*aa <= 2*r*r {
		aa++
	}

	m := abs(x) + abs(y) + aa
	fmt.Println(m)
}