#include <fstream>

using namespace std;
ifstream cin ("fractii.in");
ofstream cout ("fractii.out");
long long v[1000005];
int main()
{
    long long i,j,n,f=2,s=0;
    cin>>n;
    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];
    for (i=1;i<=n;i++)
        s+=v[i];
    cout<<s*2+1;
    return 0;
}