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