#include <fstream>
#define DIM 1000002

using namespace std;

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

int N,v[DIM];
long long S;
int main(){
    fin>>N;
    for(int i=2;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];
    for(int i=1;i<=N;i++)
        S+=v[i];
    fout<<2*S+1<<"\n";
    fin.close();fout.close();
    return 0;
}