#include<stdio.h>   
long long n,v[1000001],i,j;
  
int main()     
   {     
       FILE*f=fopen("fractii.in","r");     
       FILE*g=fopen("fractii.out","w");      
       fscanf(f,"%lld",&n);     
       for (i = 1; i <= n; ++i)   
           v[i] = i-1;   
       for (i = 2; i <= n; ++i)   
           for (j = 2*i; j <= n; j = j+i)   
               v[j] -= v[i];   
       long long nr=0;   
       for(i=1;i<=n;i++)   
             nr=nr+v[i];   
       fprintf(g,"%lld",2*nr+1);   
       fclose(f);   
       fclose(g);     
       return 0;   
}