// No.1737 One to N
// 1 <= N <= 3e5
package main

import (
	"fmt"
)

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

	k := 0
	n := N
	for p := 2; p*p <= n; p++ {
		for n%p == 0 {
			n /= p
			k += p
		}
	}
	if n > 1 {
		k += n
	}

	fmt.Println(k)
}