#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int v[1000005]
int main(){
    long long s=0;
    int n, i, j;
    f>>n;
    v[1]=1;
    for (i=2; i<=n; i++){
        v[i]=i-1;
    }
    for (i=2; i<=n; i++){
        s+=v[i];
        for (j=2*i; j<=n; j+=i){
            v[j]-=v[i];
        }
    }
    g<<s*2+1;
    return 0;
}