#include <stdio.h>
#include <stdlib.h>

int main()
{
FILE *f;
long  x[1000000];
long long r;
long i,j,n;
f=fopen("fractii.in","r");
fscanf(f,"%ld",&n);
fclose(f);
r=1;
for (i=2;i<=n;i++)
  x[i]=i-1;
for (i=2;i<=n;i++)
  {
  for (j=2*i;j<=n;j+=i)
    x[j]-=x[i];
  r+=2*x[i];
  }

f=fopen("fractii.out","w");
fprintf(f,"%lld",r);
fclose(f);

return 0;
}