#include <fstream>
#include <math.h>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long phi[1000000];
int main()
{
    long n,i,j;
    fin>>n;
    long long s=0;
    for (i = 1; i <= n; ++i)
        phi[i] = i-1;
    for (i = 2; i <= n; ++i)
        for (j = 2*i; j <= n; j += i)
            phi[j] -= phi[i];
    for(i=1;i<=n;i++)
        s+=phi[i];
    fout<<2*s+1<<"\n";
    return 0;
}