#include <fstream>
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int p[1000005];
int main()
{long long n,s=0;
    cin>>n;
    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[i];
    for(int i=1;i<=n;i++)
        s+=p[i];
    cout<<s+s+1;
    return 0;
}