package main

import (
	"fmt"
	"io"
	"os"
)

func solve(in io.Reader, out, err io.Writer) {
	var n int
	fmt.Fscan(in, &n)
	if n <= 104 {
		fmt.Fprintln(out, 4)
	} else {
		if (n/2)*2 == n {
			fmt.Fprintln(out, n)
		} else {
			fmt.Fprintln(out, n+1)
		}
	}

}

func main() {
	solve(os.Stdin, os.Stdout, os.Stderr)
}