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 "bits/stdc++.h"
using namespace std;

int main() {
    int n, res = 0;
    cin >> n;
    for (int a = 1; a < n; ++a) {
        res += (n-1)/a;
    }
    cout << res;
}