#include <cstdio>

using namespace std;
int ciur [1000000];
int main()
{
    FILE *fin=fopen ("fractii.in","r");
    FILE *fout=fopen ("fractii.out","w");
    long long n,d,sol=0,i,pos;
    fscanf (fin,"%lld",&n);
    for (d=2;d<=n;d++)
      if (ciur[d]==0)
        for (i=d;i<=n;i=i+d){
        if (ciur[i]==0)
            sol+=n/d;
        else
            sol+=n/d-1;
          ciur[i]=1;
        }
    //printf ("%lld",n);
    fprintf (fout,"%lld",n*n-sol);
    return 0;
}