#include <iostream>
#include <vector>

using namespace std;

#define int long long

struct answer {
	int a, b, c;
	answer(int _a = 0, int _b = 0, int _c = 0) {
		a = _a;
		b = _b;
		c = _c;
	}
};

signed main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int n;
	cin >> n;

	if (n <= 20) {
		vector<int> used(n + 1, false);
		vector<answer> ans;

		int f = 2, s = 3;
		while (true) {
			int j = min(n, f + s - 1);
			if (j == n) {
				n--;
			}
			while (used[j]) {
				j--;
			}
			//n = j;
			if (j * j <= f * f + s * s) {
				cout << ans.size() << endl;
				for (int i = 0; i < ans.size(); i++) {
					cout << ans[i].a << " " << ans[i].b << " " << ans[i].c << endl;
				}
				return 0;
			}
			used[f] = true;
			used[s] = true;
			used[j] = true;
			ans.push_back({ f, s, j });

			while (f < n && used[f]) {
				f++;
			}
			s = f + 1;
			while (s < n && used[s]) {
				s++;
			}
			if (f >= n && s >= n) {
				cout << ans.size() << endl;
				for (int i = 0; i < ans.size(); i++) {
					cout << ans[i].a << " " << ans[i].b << " " << ans[i].c << endl;
				}
				return 0;
			}
		}

		return 0;
	}

	vector<answer>v;
	int x = n / 3;
	int cnt = 0;
	for (int i = n; ; i -= 4) {
		if (x - cnt == 2) {
			break;
		}
		v.push_back(answer( i, i - 2, x - cnt ));
		if (x - cnt - 1 == 2) {
			break;
		}
		v.push_back(answer(i - 1, i - 3, x - cnt - 1));
		cnt += 2;
	}

	cout << v.size() << endl;
	for (int i = 0; i < v.size(); ++i) {
		cout << v[i].a << ' ' << v[i].b << ' ' << v[i].c << endl;
	}

	return 0;
}