#include <fstream>
#include<iostream>
using namespace std;
int n,v[1000100];
int main()
{
    ifstream in;in.open("fractii.in");
    ofstream ou;ou.open("fractii.out",ofstream::out);
    long long i,j,flag=0;
    in>>n;
    for(i=1;i<=n;i++)v[i]=i-1;
    for(i=1;i<=n;i++)
    for(j=2;j*i<=n;j++)
        v[i*j]-=v[i];
    for(i=1;i<=n;i++)flag+=2*v[i];
    flag++;
    ou<<flag;
    in.close();ou.close();
    return 0;
}