#include<stdio.h>

using namespace std;

int fi(int n)
     {
       int result = n;
       for(int i=2;i*i <= n;i++)
       {
         if (n % i == 0) result -= result / i;
         while (n % i == 0) n /= i;
       }
       if (n > 1) result -= result / n;
       return result;
     }
int main()
{
    FILE *in,*out;
    in=fopen("fractii.in","r");
    out=fopen("fractii.out","w");
    int nr=1,i,n;
    fscanf(in,"%d",&n);
    for(i=2;i<=n;i++)
    nr+=2*fi(i);
    fprintf(out,"%d",nr);
    return 0;
}