#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
long long v,a[1000001],i,j,n;
void euler()
{
    for(i=1;i<=n;i++)
        a[i]=i;
    for(i=2;i<=n;i++)
        if(a[i]==i)
            for(j=i;j<=n;j=j+i)
                a[j]=a[j]*(i-1), a[j]=a[j]/i;
}
int main()
{
    in>>n;
    euler();
    for(i=2;i<=n;i++)
        v=v+a[i];
    out<<(v*2)+1;
    return 0;
}