#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
 
int fr[1000050];
 
int main() {
 
    int i,j,n;
    long long nr=0;
 
    f>>n;
    for(i=1;i<=n;i++)
        fr[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
            fr[j]-=fr[i];
    for(i=2;i<=n;i++)
        nr+=fr[i];
 
    g<<2*nr+1<<"\n";
 
    return 0;
}