#include<fstream.h>
#include<math.h>
long int s,i,j,n,k,v[1000001],prim[10000],contor;
int main()
{
ifstream in("fractii.in");
ofstream out("fractii.out");
in>>n;
s=n*n;
k=1;
for(i=2;i<=n;i=i+1)
if(prim[i]==0)
	       {for(j=i+i;j<=n;j=j+i)
		prim[j]=1;
		v[k]=i;
		k=k+1;
		}
for(i=1;i<=k-1;i=i+1)
s=s-int(n/v[i])*int(n/v[i])+int(n/v[i]);
s=s-n+1;
out<<s<<" ";
in.close();
out.close();
return 0;
}