#include <stdio.h>
#include <stdlib.h>
#include <math.h>
long long S;
int main()
{
    FILE *f,*g;
    f=fopen("fractii.in","r");
    g=fopen("fractii.out","w");

    long long N;
    long long i,e[1000001],j;
    fscanf(f,"%lld",&N);
   for(i=1;i<=N;i++)
    e[i]=i-1;
       for(i=2;i<=N;i++)
            for(j=2*i;j<=N;j+=i)
           e[j]=e[j]-e[i];

      for(i=1;i<=N;i++)
           S+=2*e[i];
       S+=1;

    fprintf(g,"%lld",S);

    return 0;
}