#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, v[1000000+10], i, j;
long long sum;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++) v[i]=i-1;
    for(int i=2;i<=n;i++)
    {
        sum+=v[i];
        for(j=2*i;j<=n;j+=i)
        {
            v[j]-=v[i];
        }
    }
    fout<<2*sum+1;
}