#include <fstream>

using namespace std;

int N;
int dp[1000005];
long long ans;

int main() {
    ifstream in("fractii.in"); in>>N; in.close();
    for(int i = 2; i <= N; i++) {
        dp[i] += i - 1;
        for(int j = 2 * i; j <= N; j += i) dp[j] -= dp[i];
        ans += dp[i];
    }
    ofstream out("fractii.out"); out<<2LL * ans + 1; out.close();
    return 0;
}