Clipboard#3040
Bart Simpson, from the animated series "The Simpsons", has been assigned a punishment for skipping classes: he must send an email to the school principal. In this email, Bart is required to type the phrase "I will not skip school anymore" times. The principal believes that this exercise will deter Bart from skipping school in the future. Naive principal!
Instead of typing the phrase times, Bart writes it once and then uses the clipboard to replicate it. In one operation, Bart can either copy the entire current content of the email to the clipboard, or paste the text from the clipboard into the email.
Write a program that, given the number of times the phrase must appear in the email, determines the minimum number of clipboard operations Bart needs to perform to achieve the required number of phrases.
The input consists of a single number , the number of times the phrase "I will not skip school anymore" must appear in the email. The number is a natural number and does not exceed 2 \cdot 10^9.
Output a single integer, the minimum number of clipboard operations needed for the email to contain exactly phrases.
Explanation. After Bart writes the first phrase, he can perform the following clipboard operations:
Copy the current content of the email ( phrase).
Paste the copied text (the email now has phrases).
Paste the copied text (the email now has phrases).
Paste the copied text (the email now has phrases).
Copy the current content of the email ( phrases).
Paste the copied text (the email now has phrases).
Paste the copied text (now the email contains the required phrases).
Example 1