#include <iostream>
#include <cstdio>
#include <unordered_map>
using namespace std;
int n,p=0;
unordered_map<float,bool>m;
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(float i=1;i<=n;i++)
    {
        int k=((int)i%2==0)?2:1;
        for(float j=1;j<=n;j+=k)
        {
            if(!m[i/j])
            {
                m[i/j]=1;
                p++;
            }
        }
    }
    printf("%d",p);
    return 0;
}