#include <fstream>
#define nmax 1000003

using namespace std;

int n,i,j;

long long T=0;
int fi[nmax];


ifstream cin("fractii.in");
ofstream cout("fractii.out");


int main()
{
    cin>>n;
    for (i=1; i<=n; i++)
        fi[i] = i-1;
    fi[1]=1;
    for (i=2; i<=n; i++)
        for (j=i+i; j<=n; j+=i)
            fi[j] -= fi[i];
    for(i=1; i<=n; ++i)
        T+=fi[i];
    cout<<2*T-1;
    cin.close();
    cout.close();
    return 0;
}