https://old.ynoip.cn/p/81517

#include <iostream>
#include <algorithm>
using namespace std;
int wd[1000000];

int main(void) {
	int N, M;
	cin >> N >> M;
	if (N > 20 || N < 5 || M >= 1000 || M <= 5) {
		printf("NULL");
		return 0;
	}

	for (int i = 0, u; i < M; i++) {
		cin >> u;
		wd[u]++;
	}
	for (int i = 1, n, maxn = 0; i <= N; i++) {
		for (int u = N; u >= 1; u--) {
			if (wd[u] >= 0 && wd[u] >= maxn) {
				maxn = wd[u];
				n = u;
			}
		}
		printf("%d %d %d\n", i, maxn, n);
		wd[n] = -1;
		maxn = 0;
	}
	return 0;
}