#include <iostream>
#include <fstream>

using namespace std;
int phi[1000010];
int main()
{ifstream fin("fractii.in");
ofstream fout("fractii.out");
int i,j,n;
long long nr;
fin>>n;
for(i=1;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];
for(i=2,nr=0;i<=n;i++)
    nr+=phi[i];
fout<<2*nr+1;
    return 0;
}