#include <iostream>

#include <fstream>

using namespace std;


long long n, sir[1000005], rez;


ifstream f("fractii.in");

ofstream g("fractii.out");


void solve()

{

int aux=n/2;

for (int i=2; i<=n; ++i)

{

rez+=2*sir[i];

for (int j=2*i; j<=n; j+=i)

{

sir[j]-=sir[i];

}

}

g << rez+1;

}


int main()

{

f >> n;

for (int i=2; i<=n; ++i)

{

sir[i]=i-1;

}

solve();

return 0;

}