#include <fstream>
#include <iostream>
using namespace std;
 
ifstream inFile("fractii.in");
ofstream outFile("fractii.out");
 
long int v[1000005];
 
int main()
{
    long int n,i,k;
    long long int s=0;
    inFile >> n;
    for(i = 1; i <= n/2; 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];
}
for (i==n/2+1;i<=n;i++)
s=s+v[i]+i-1;
    s=s*2+1;
    outFile << s;
}