#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long long k,n,i,j;
int a[1000001];
int main()
{f>>n;
for(i=1;i<=n;++i)
	a[i]=i-1;
for(i=2;i<=n;++i)
{for(j=2*i;j<=n;j=j+i)
	a[j]=a[j]-a[i];
k=k+a[i];
}
g<<2*k+1<<'\n';
f.close();
g.close();
return 0;
}