#include <iostream>
#include <fstream>
using namespace std;
int phi[1000010];
int main() {
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    int i,j,n;
    long long nr;
    fin>>n;
    for(i=1;i<=n;i++)
        phi[i]=i-1; for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
        phi[j]-=phi[i];
    for(i=2,nr=0;i<=n;i++)
        nr+=phi[i];
    fout<<2*nr+1;
    return 0;
}