#include <bits/stdc++.h>
#define ULL unsigned long long

using namespace std;

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

int n;
int euler[1000001];
ULL sum;

int main()
{
    in>>n;

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

    for(int i=2;i<=n;i++)
    {
        for(int j=i*2;j<=n;j+=i)
            euler[j]-=euler[i];

        sum+=euler[i];
    }

    out<<sum*2+1;

    return 0;
}