#include <fstream>

using namespace std;

ifstream cin("fractii.in");
ofstream cout("fractii.out");

int n,i,j;
long long int nr;
int v[1000005];

int main()
{
    cin>>n;
    for(i=2;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++)
        nr+=v[i];
    cout<< 2*nr+1 << '\n';
    return 0;
}