#include <fstream.h>
#include <iostream.h>
ifstream f("fractii.in");
ofstream g("fractii.out");
long long a[1000000];
int main()
{long long nr,n,i,j;
 f>>n; nr=0;
 for(i=1;i<=n;i++) a[i]=i-1;
 for(i=2;i<=n;i++) {nr+=a[i]; for(j=i*2;j<=n;j+=i) a[j]-=a[i]; }
 nr=2*nr+1;
 g<<nr; return 0;}