#include <fstream>

using namespace std;

ifstream cin("fractii.in");
ofstream cout("fractii.out");

#define MAXN 1000000

long long sp[MAXN+1];

int main() {
    int n;
    cin>>n;
    int i, j;
    for(i=2; i<=n; i++) sp[i]=i-1;
    long long ans;
    ans=0;
    for(i=2; i<=n; i++) {
        ans+=sp[i];
        for(j=i+i; j<=n; j+=i) sp[j]-=sp[i];
    }
    cout<<2*ans+1;
}