#include <fstream>
#include <iostream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");
long long nr;
int main()
{
    unsigned long n,i,j,v[1000001];
    fin>>n;
    fin.close();
    for(i=1;i<=n;++i) {
        v[i] = i;
    }
    for(i=1;i<=n;++i) {
        nr+=v[i];
        for(j=i+i;j<=n;j+=i)
            v[j]-=v[i];
    }
    fout<<2*nr-1;
    fout.close();
    return 0;
}