#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream in("fractii.in");
    ofstream out("fractii.out");
long long n,i,j,s;
int pi[1000001];
    in>>n;
    for(i=1;i<=n;i++)
        pi[i]=i-1;
    pi[1]=1;
    for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j+=i)
            pi[j]-=pi[i];
    for(i=1;i<=n;i++)
        s+=pi[i];
    out<<s*2-1;
    in.close();
    out.close();
    return 0;
}