#include <iostream>
#include <fstream>

using namespace std;
const char InFile[]="fractii.in";
const char OutFile[]="fractii.out";
const int DIMN=1000005;

ifstream in(InFile);
ofstream out(OutFile);
int v[DIMN];

int main()
{
    long long int sum;
    int n;
    in>>n;
    for(int i=1;i<=n;++i)
        v[i]=i-1;
    for(int i=2;i<=n;++i)
            for(int j=i+i;j<=n;j+=i)
                 v[j]-=v[i];
    sum=1;
    for(int i=1;i<=n;++i)
        sum+=2*v[i];
    out << sum <<endl;
    return 0;
}