#include<iostream>
#include<cstdio>
#include<map>
using namespace std;
const int MAXN=50000+10;
const long long BASE=10e5;
map<long long,bool> v;
long long n,ans;
int main(){
freopen("sendtable.in","r",stdin);
freopen("sendtable.out","w",stdout);
cin>>n;
for(int x=1;x<=n;x++) for(int y=1;y<=n;y++)
if(!v[x*BASE+y]) {
ans++;
int k=1;
for(k=1;x*k<=n&&y*k<=n;k++) v[x*k*BASE+y*k]=1;
}
cout<<ans;
}