#include <bits/stdc++.h>

using namespace std;

int euler[1000005];

int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    int n;
    long long int cnt = 0;
    fin >> n;
    for (int i = 2;i <= n;i++)
        euler[i] = i - 1;
    for(int i = 2;i <= n;i++)
    {
        cnt += euler[i];
        for(int j = 2 * i;j <= n;j += i)
            euler[j] = euler[j] - euler[i];
    }
    fout << 2 * cnt + 1;
    return 0;
}