#include <iostream>
#include <bitset>
#include <fstream>
#include <cstdio>
#include <cstdlib>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int main()
{
    int i, j, N;
    f>>N;
    int *v = (int*)malloc((N+1)*sizeof(int));
    long long total = 0;
    for(i=2; i<=N; i++)
        v[i]=i-1;
    for(i=2; i<=N; i++)
    {
        for(j=2*i; j<=N; j+=i)
            v[j]=v[j]-v[i];
    }
    for(i=2; i<=N; i++)
       total+=v[i];
    total*=2;
    ++total;
    g<<total;
    free(v);
    f.close();
    g.close();
    return 0;
}