#include<iostream>
#include<fstream>
#include<algorithm>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int i,j,v[1000010],n;
long long s;

int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=2*i;j<=n;j+=i)
            v[j]-=v[i];
    }
    for(i=1;i<=n;i++)
        s=1LL*s+v[i];
    fout<<2*s+1;
    fin.close();
    fout.close();
    return 0;
}