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#include <iostream>
#include <fstream>
using namespace std;

const int VMAX = 1000010;
 
ifstream fin("fractii.in");
ofstream fout("fractii.out");
 
int N;
long long int sol;
int euler[VMAX];
 
int main() {
    fin >> N;
    for (int i = 2; i <= N; i++)
        euler[i] = i - 1;
 
    for (int i = 2; i <= N; i++) {
        sol += euler[i];
        for (int j = 2 * i; j <= N; j += i)
            euler[j] -= euler[i];
    }
    fout << 2 * sol + 1 << '\n';
    
    fout.close();
    return 0;
}