#include <fstream>

using namespace std;

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

int n;
long long sum;
int p[1000010];

int phi(){
    for(int i=1;i<=n;++i) p[i]=i-1;
    for(int i=2;i<=n;++i){
        for(int j=2*i;j<=n;j+=i) p[j]=p[j]-p[i];
        sum+=p[i];
    }
    sum*=2;
    ++sum;
    fout<<sum;

}

int main(){
    fin>>n;
    phi();


    return 0;
}