package main

import . "fmt"
import . "math/big"

func main() {
	var n int64
	Scan(&n)
	Println(solve(n))
}

func check() {
	for n := 1; n < 10000; n++ {
		s:=solve(int64(n))
		b:=bruteforce(n)
		if s!= b {
			Println(n, s, b)
			return
		}
	}
	Println("ok")
}

func solve(nn int64) int64 {
	n:=NewInt(nn)
	x:=new(Int).Sqrt(n)
	if x.Cmp(new(Int).Div(n, x))==0 {
		return x.Add(x,x).Sub(x,NewInt(1)).Int64()
	} else {
		return x.Add(x,x).Int64()
	}
}

func bruteforce(n int) int64 {
	m:=map[int]bool{}
	for k:=1; k<=n; k++ {
		m[n/k]=true
	}
	return int64(len(m))
}