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 main()
{
    int N;
    int cnt=0;
    cin >> N;
    for(int a=1; a<=N; a++)
    {
        cnt+= (N-1)/a;
    }

    cout << cnt;
}