#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n,i,j,v[1000001];
long long s;
int main(){
    fin>>n;
    for(i=1;i<=n;i++){
        v[i]=i-1;
    }
    for(i=2;i<=n;i++){
        for(j=2*i;j<=n;j+=i){
            v[j]-=v[i];
        }
    }
    for(i=1;i<=n;i++){
        s+=v[i]*2;
    }
    fout<<s+1<<"\n";


    return 0;
}