#include<fstream>
#define LMAX 1000002
using namespace std;
unsigned int euler(unsigned int length){
    unsigned int phi[LMAX],i,j,sum = 0;
    for(i = 1; i <= length; i++){
        phi[i] = i-1;
    }
    for(i = 2; i <= length; i++){
        for(j = 2*i; j<= length; j+=i){
            phi[j] -= phi[i];
        }
    }
    for(i = 1; i <= length; i++){
        sum += phi[i];
    }
    return sum;
}
int main(){
    unsigned int n;
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>n;
    fout << euler(n)*2 + 1<<"\n";
    fin.close();
    fout.close();
    return 0;
}