#include <bits/stdc++.h>

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int phi[1000005];
int main()
{
    long long n,i,j,ans=0;
    f>>n;
    for(i=1;i<=n;i++)
        phi[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j+=i)
        phi[j]-=phi[i];
    for(i=1;i<=n;i++)
        ans+=phi[i];
    g<<2*ans+1;

    return 0;
}