#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;

struct group {
	int ppl;
	int x, y;
} g[101];

int main() {
	int N, M;
	freopen("bdz.in", "r", stdin);
	freopen("bdz.out", "w", stdout);

	cin >> N >> M;

	for (int i=1; i<M+1; i++) {
		cin>> g[i].ppl >> g[i].x >> g[i].y;
	}
	int currentPeople(0), max(0);

	for (int i=1; i<N+1; i++) {
		for (int j=1; j<M+1; j++) {
			if (g[j].x == i) {
				currentPeople += g[j].ppl;
				if (currentPeople > max) {
					max = currentPeople;
				}
			}
			if (g[j].y == i) currentPeople -= g[j].ppl;
		}
	}

	cout << ceil((double)max/(double)64) << endl;
	return 0;
}