#include <fstream>

using namespace std;

ifstream fin("fractii.in");
ofstream gout("fractii.out");

int main()
{
    int n, i, j;
    long long cnt=0;
    fin >> n;
    int v[n];
    for(i = 1; i <= n; i++)
        v[i] = i - 1;
    for(int i = 2; i <= n; ++i)
        for(j = 2 * i; j <= n; j+=i)
            v[j] -= v[i];
    for(i = 2; i <= n; i++)
        cnt += v[i];
    gout << 2*cnt+1;
}