#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, v[1000002],i,j,k,ok,minim,maxim,x,y;
long long r;
int main(){
    fin>>n;
    for(i=2;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++){
        r=r+v[i];
        for(j=i+i;j<=n;j+=i)
        v[j]=v[j]-v[i];
    }
    fout<<r*2+1;
    return 0;

}