#include <iostream>
using namespace std;
int main(){

	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);

    int n;
    long long sum = 0;
    
	cin >> n;
	int *numitori;

	numitori = new int[n+1];

    for(int i = 2; i <= n; ++i)
        numitori[i] = i-1;
  
    for(int i = 2; i <= n; ++i)
    {
        sum += numitori[i];
        for (int j = 2*i; j <= n; j += i)
            numitori[j] -= numitori[i];
    }
   cout << 2 * sum + 1;

   return 0;
}