#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int n;
int p[1000010];
long long r;
int main()
{
    in>>n;
    p[1]=1;
    for(int i=2;i<=n;++i)
        p[i]=i-1;
    for(int i=2;i<=n/2;++i)
        for(int j=2;j*i<=n;++j)
            p[i*j]-=p[i];
    for(int i=1;i<=n;++i)
        r+=p[i];
    out<<r*2-1;
    return 0;
}