#include<fstream>

using namespace std;

int n,i;
int a[1000001];
long long r;

ifstream f("fractii.in");
ofstream g("fractii.out");

void pi()
{
 int j,i;
 for(i=1;i<=n;++i){a[i]=i-1;}
 for(i=2;i<=n;++i){for(j=2*i;j<=n;j+=i){a[j]-=a[i];}}    
}

int main()
{
 f>>n;
 pi();
 r = 1;
 for(i=1;i<=n;i++){r+=2*a[i];}
 g<<r;
 f.close();g.close();
 return 0;   
}