#include<fstream>
using namespace std;

#define dim 100000
int n;
long long sol;
int v[dim];
int main (){
     ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>n;
    for(int i=1;i<=n;++i)
    v[i]=i-1;
    for(int i=2;i<=n;++i)
    for(int j=2;j<=n;++j)
        v[i*j]=v[i*j]-v[i];
    for(int i=2;i<=n;++i)
        sol=sol+v[i];
        sol=sol*2+1;
    fout<<sol;
     fin.close();
    fout.close();

/*
int cmmdc (int a, int b) {
while (a!=b)
{if (a>b) a=a-b; else b=b-a;

}
return b;
}
int main(){
    int n, i, j, k=0;
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>n;
    for(i=1;i<=n;i++)
    for(j=1;j<=n;j++)
    { if( cmmdc(i,j)==1) {k=k+1;}
    }
    fout<<k;
    fin.close();
    fout.close();*/
}