#include <fstream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int prime[1000001],n,i,j;
long long sol;

int main(){
    fin>>n;
    for(i=1;i<=n;i++)
        prime[i]=i-1;

    for(i=1;i<=n;i++){
        for(j=2*i;j<=n;j+=i)
            prime[j]-=prime[i];
        sol+=prime[i];
    }

    fout<<1+2*sol;

    return 0;
}