#include<fstream>
using namespace std;


int main(){
int i,j,n,v[1000005];
long long cate=0;
ifstream f;
f.open("fractii.in");
f>>n;
f.close();
for (i = 2; i <= n; ++i)
v[i] = i-1;
for (i = 2; i <= n; ++i)
{
for (j = 2*i; j <= n; j+=i)
v[j] -= v[i];
cate+=v[i];
}
ofstream g;
g.open("fractii.out");
g<<cate;
g.close();
return 0;
}