#include <iostream>
#include <fstream>
#define maxn 1000005
using namespace std;

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

long long n, sieve[maxn];

int main(){
	in >> n;
	for(int i=2;i<=n;i++){
		while(sieve[i]!=0) i++;
		int cnt=n/i;
		for(int j=1;j*i<=n;j++)
            if(sieve[j*i]==0)
			sieve[j*i]+=cnt;
            else
            sieve[j*i]+=(cnt-1);

	}


	long long result=0;
	for(int i=1;i<=n;i++){
		result+=(n-sieve[i]);
	}
    out<<result;
	return 0;
}