#include <iostream>
#include <fstream>
#define Nmax 1000005
#define zeros(x) ((x^(x-1))&x)

using namespace std;
/*
ifstream f("stramosi.in");
ofstream g("stramosi.out");*/

ifstream f("fractii.in");
ofstream g("fractii.out");

int dp[Nmax], n;
long long sum;

int main()
{
    f >> n;

    for (int i = 2; i <= n+1; i++)
        dp[i]=i-1;

    for (int i = 2; i <= n; i++)
    {
        sum+=dp[i];
        for (int j = i+i; j <= n; j+=i)
            dp[j]-=dp[i];
    }

    g << 2*sum+1;

    return 0;
}