#include<fstream>

using namespace std;

FILE*in;
ofstream out("fractii.out");

long n;
long long nr_fractii;
long FR[1000002];

void read()
{
    in=fopen("fractii.in", "r");

    fscanf(in, "%ld", &n);
}

void solve()
{
    for (long i=1; i<=n; i++)
        FR[i]=i-1;

    for (long i=2; i<=n/2; i++)
        for (long j=2*i; j<=n; j+=i)
            FR[j]-=FR[i];
    for (long i=1; i<=n; i++)
        nr_fractii+=FR[i];
}

void show()
{
    out<<nr_fractii*2+1;
}

int main()
{
    read();
    solve();
    show();

    return 0;
}