// No.1992 Tendon Walk
package main

import (
	"fmt"
	"math"
)

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

	const a = 2
	const b = -1
	set := []int{a, a, b, b, a, b, b}
	pos, ans := 0, 0.0
	for {
		for _, v := range set {
			pos += v
			ans += math.Abs(float64(v))
			if pos == x {
				goto Exit
			}
		}
	}
Exit:
	fmt.Println(ans)
}