#include <fstream>

using namespace std;

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

int euler (int nr) {
    int d=2, cl=nr;
    while(nr>1){
        if(nr%d==0){
            cl=cl/d*(d-1);
            while(nr%d==0){
                nr/=d;

            }
        }
        ++d;
        if(d*d>nr)
            d=nr;
    }
    return cl;
}

int main()
{
    int n;
    unsigned long long s=0;
    cin>>n;

    for(int i = 1;i<=n;++i){
        s+=euler(i);
    }

    cout<<2*s-1;

    return 0;
}