#include<stdio.h>   
  
int main()   
{   
  
freopen("fractii.in","r",stdin);   
  
freopen("fractii.out","w",stdout);   
long long N,j,phi[1000001],i,s;   
scanf("%lld",&N);   
  
for (i = 1; i <= N; ++i)   
    phi[i] = i-1;   
  
for (i = 2; i <= N; ++i)   
    for (j = 2*i; j <= N; j += i)   
    phi[j] -= phi[i];;   
s=0;   
for(i=2;i<=N;i++)   
  s=s+phi[i];   
  
printf("%lld",(2*s)+1);   
  
return 0;   
}