#include <bits/stdc++.h>
using namespace std;

vector<vector<int>> dp;
vector<vector<pair<int, int>>> p;

void update(int a, int b, int c, int d, int val)
{
	if (dp[a][b] >= val) return;
	dp[a][b] = val;
	p[a][b] = {c, d};
}

int main()
{
	int n;
	cin >> n;
	dp.assign(n + 1, vector<int>(128, 0));
	p.assign(n + 1, vector<pair<int, int>>(128, {0, 0}));

	for(int i = 1; i <= n; i++)
		for(int j = 0; j < (1 << 7); ++j)
		{
			update(i, j >> 1, i - 1, j, dp[i - 1][j]);
			if ((j & 1) || (j & 8)) continue;
			update(i, (j >> 1) + 64, i - 1, j, dp[i - 1][j] + 1);
		}

	int id = 0;
	for (int i = 1; i < 128; i++)
		if (dp[n][i] > dp[n][id]) id = i;

	vector<int> ans;
	int mask = id;
	int now = n;
	while(now)
	{
		pair<int, int> from = p[now][mask];
		if (dp[now][mask] > dp[from.first][from.second])
			ans.push_back(now);
		now = from.first;
		mask = from.second;
	}

	reverse(ans.begin(), ans.end());
	cout << (int)ans.size() << endl;
	for(auto i: ans)
		cout << i << ' ';
	cout << endl;
	return 0;
}