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

    cout << x << endl;
}