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 <cstdio>
int main(){
    int n,ans=0;scanf("%d",&n);
    for(int a=1;a<=n;a++) for(int b=1;b*a<n;b++) ++ans;
    printf("%d\n",ans);
    return 0;
}