Given is a positive integer N. How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

* 2 \leq N \leq 10^6
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N


Output

Print the answer.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985
#include <iostream>
using namespace std;
int n;
long long cnt = 0;
int main()
{
    cin >> n;
    for (int i = 1; i <= n - 1; ++i) {
        cnt += (n - 1) / i;
    }
    cout << cnt;
}