#include <fstream>

using namespace std;
ifstream cin ("fractii.in");
ofstream cout ("fractii.out");
long long phi[1000003];
int main()
{
    long long n,i,j;
    cin>>n;
    phi[1]=1;
    for(i=2;i<=n;++i)
        phi[i]=i-1;
    for(i=2;i<=n;++i)
        for(j=i*2;j<=n;j+=i)
            phi[j]-=phi[i];
    long long s=0;
    for(i=1;i<=n;++i)
        s+=phi[i];
    cout<<s*2-1;
    return 0;
}