#include <bits/stdc++.h>
#define ll long long
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int a[1000001];
int i,j,n;
ll sol;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)a[i]=i-1;
    for(i=2;i<=n;i++)
    {
        sol+=a[i];
        for(j=2*i;j<=n;j+=i)
            a[j]-=a[i];
    }
    fout<<2*sol+1<<"\n";
    return 0;
}