#include <iostream>
#include <fstream>
using namespace std;
int i,a[9999999],j,n;
long long s;
int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");

    fin>>n;
    for(j=1; j<=n; ++j)
        a[j]=j-1;
    for(i=2; i<=n; ++i)
    {
        for(j=i+i; j<=n; j=j+i)
            a[j]=a[j]-a[i];
    }
    for(i=2; i<=n; ++i)
        s=s+a[i];
    fout<<s*2+1;
    return 0;
}