#include <bits/stdc++.h>
using namespace std;
long long F[1000100],N;
int main(){
	ifstream cin("perm.in");
	ofstream cout("perm.out");
    cin >> N;
    for(int i = 2;i<=N;i++) F[i] = i;
    for(int i = 2;i<=N;i++)
		if(F[i] == i) for(int j = i;j<=N;j+=i) F[j]/=i,F[j]*=(i-1);
	for(int i = 3;i<=N;i++) F[i]+=F[i-1];
    cout << 2*F[N]+1;
    return 0;
}