#include <bits/stdc++.h>

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

int n,i,j,v[1000001]; long long sum;
int main()
{
    cin>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=1;i<=n;i++)
        for(j=2*i;j<=n;j+=i)
            v[j]-=v[i];
    for(i=1;i<=n;i++)
        sum+=v[i];
    cout<<2*sum+1;

    return 0;
}