package main

import (
    "fmt"
    "math"
)

func main(){
    var x, y, l float64
    var cnt int
    fmt.Scan(&x)
    fmt.Scan(&y)
    fmt.Scan(&l)
    if y < 0 {
        if x != 0 {
            cnt += 2
        } else if x == 0 {
            cnt += 3
        }
    } else if y == 0 && x != 0 {
        cnt++
    } else if x != 0 {
        cnt++
    }

    cnt += int(math.Ceil(math.Abs(x) / l))
    cnt += int(math.Ceil(math.Abs(y) / l))
    fmt.Println(cnt)
}