#include <bits/stdc++.h>

using namespace std;

long long MOD=9901;

ifstream fin ("fractii.in");
ofstream fout ("fractii.out");

int n,s;
int a[1000000];

int main()
{
    fin >> n;
    for (int i=1;i<=n;i++)
    {
        if (!a[i])
            {
                s+=i-1;
                for (int j=2*i;j<=n;j+=i)
                {
                    if (a[j])
                        a[j]-=a[j]/i;
                    else
                        a[j]=j-j/i;
                }
            }
            else
                s+=a[i];
    }
    fout << 2*s+1;
    return 0;
}