#include <iostream>
#include <fstream>

using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");

const int nmax=1000010;
long long int n,ans=0,d[nmax];

int main(){
in >>n;

for(int i=2;i<=n;i++) d[i]=i-1;
   
for(int i=2;i<=n;i++){
	ans+=d[i];
	
	for(int j=2*i;j<=n;j+=i) d[j]-=d[i];	
}
out <<2 * ans + 1<<"\n";

return 0;
}