Divisor Subtraction
Description
You are given an integer number $n$. The following algorithm is applied to it:
- if $n = 0$, then end algorithm;
- find the smallest prime divisor $d$ of $n$;
- subtract $d$ from $n$ and go to step $1$.
Determine the number of subtrations the algorithm will make.
The only line contains a single integer $n$ ($2 \le n \le 10^{10}$).
Print a single integer — the number of subtractions the algorithm will make.
Input
The only line contains a single integer $n$ ($2 \le n \le 10^{10}$).
Output
Print a single integer — the number of subtractions the algorithm will make.
Samples
5
1
4
2
Note
In the first example $5$ is the smallest prime divisor, thus it gets subtracted right away to make a $0$.
In the second example $2$ is the smallest prime divisor at both steps.