#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int Solution[1000002],N;
void Eratostene()
{
    int i,j;
    for(i=1;i<=N;i++)
        Solution[i]=i-1;
    for(i=2;i<=N;i++)
        for(j=i+i;j<=N;j+=i)
            Solution[j]-=Solution[i];
}
void Print()
{
    int i;
    long long Result=0;
    for(i=1;i<=N;i++)
        Result+=(long long)Solution[i];
    g<<Result*2+1<<"\n";
}
int main()
{
    f>>N;
    Eratostene();
    Print();
    return 0;
}