#include <string>
#include <iostream> 
#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <vector>
#include <iomanip>
#include <map>
#include <sstream>
#include <iterator>
#include <set>
#include <queue>
#include <cstring>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

typedef vector<int> vi;
typedef pair<int, int> ii;


int main()
{
	//freopen("C:\\Users\\Despondency\\Desktop\\in.txt","r",stdin);
	ios_base::sync_with_stdio(0); //care for getchar()
	cin.tie(0);
	int n;
	cin >> n;
	
	for (int i = 1; i <= n / 2; i++)
	{
		cout << i << " ";

	}

}


#include <string>
#include <iostream> 
#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <vector>
#include <iomanip>
#include <map>
#include <sstream>
#include <iterator>
#include <set>
#include <queue>
#include <cstring>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

typedef vector<int> vi;
typedef pair<int, int> ii;


int main()
{
	//freopen("C:\\Users\\Despondency\\Desktop\\in.txt","r",stdin);
	ios_base::sync_with_stdio(0); //care for getchar()
	cin.tie(0);
	int n;
	cin >> n;
	cout << n / 2 << endl;
	for (int i = 1; i <= n / 2; i++)
	{
		cout << i << " ";

	}

}

#include <string>
#include <iostream> 
#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <vector>
#include <iomanip>
#include <map>
#include <sstream>
#include <iterator>
#include <set>
#include <queue>
#include <cstring>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

typedef vector<int> vi;
typedef pair<int, int> ii;


int main()
{
	//freopen("C:\\Users\\Despondency\\Desktop\\in.txt","r",stdin);
	ios_base::sync_with_stdio(0); //care for getchar()
	cin.tie(0);
	int n;
	cin >> n;
	cout << n / 2 << endl;
	for (int i = 1; i <= n / 2; i++)
	{
		cout << i << " ";

	}

}