#include <fstream>

using namespace std;

ifstream inFile("fractii.in");
ofstream outFile("fractii.out");

long long v[1000005];

int main()
{
    long long n,i,k,s;
    inFile >> n;

    for(i = 1; i <= n; i++)
	{
    	k=2;
        v[i]=v[i]+i-1;
    while (k*i<=n){
    	v[i*k]=v[i*k]-v[i];
    	k++;
    }
 s=s+v[i];
}
    s=s*2+1;
    outFile << s;
}