/*
 * author: pavveu
 * task: PA Runda 1 - Mieszanie Kolorow [B]
*/

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

#define FOR(iter, val) for(int iter = 0; iter < (val); iter++)
#define all(x) begin(x), end(x)


void go() {
	int n, m; cin >> n >> m;
	vi colored[3];
	FOR(c, 3) colored[c].assign(n, 0);

	FOR(q, m) {
		// 1 indexed
		int l, r, c; 
		cin >> l >> r >> c;
		l--;
		c--;

		colored[c][l] += 1;
		if ( r < n ) colored[c][r] -= 1;
	}

	auto is_green = [&](int y, int n, int c){
		return ( y > 0 && n > 0 && c == 0 );
	};

	FOR(c, 3) for (int i = 1; i < n; i++) colored[c][i] += colored[c][i - 1];

	int green_cnt { 0 };
	FOR(i, n) green_cnt += is_green(colored[0][i], colored[1][i], colored[2][i]);

	cout << green_cnt << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	go();

	return 0;
}