#include<iostream.h>
#include<fstream.h>
fstream f("fractii.in",ios::in)
fstream g("fractii.out",ios::out)
main()
{
int n,i,j,k=0,a;
f>>n;
for(i=1;i<=n;i++)
    a[i]=i;
for(i=2;i<=n;i++)
    if (a[i]==i)
      for(j=1;j*i<=n;j++)
       	a[j*i]=a[j*i]*(i-1)/i;
k=0;
for(i=1;i<=n;i++)
k+=a[i];
g<<k;
return o;
}