#include <stdio.h>  
    #define Nmax 1000001  
      
    long long N, i, j, c[Nmax], rez;  
      
    int main()  
    {  
        fscanf(fopen("fractii.in", "r"), "%lld", &N);  
        for (i = 1; i<=N; ++i) c[i] = i;  
       for(i = 2; i <=N; ++i)  
           if (c[i] == i)  
           for (j = 1; i*j<=N; ++j)  
               c[i*j] *= (double)(i-1) / i;  
       for (i = 2; i<=N; ++i) rez+=c[i];  
      fprintf (fopen("fractii.out", "w"), "%lld", 2*rez+1);  
      return 0;  
  }