#include <iostream>
#include <fstream>
#define NMax 1000005
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");
 int fr[NMax];
int main()
{
    long long sol=0;
    int N;
    fin>>N;
    int i,j;
    for(i=1;i<=N;++i)
    {
        fr[i]=i-1;
    }
    for(i=2;i<=N;++i)
    {
        for(j=i+i;j<=N;j+=i)
        {
            fr[j]-=fr[i];
        }
    }
    for(i=2;i<=N;++i)
        sol+=fr[i];
    sol*=2;
    sol++;
    fout<<sol<<"\n";
    return 0;
}