#include <fstream>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
const int nmax = 1000006;
int a[nmax];

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