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#include <bits/stdc++.h>
using namespace std;
int n, m, l, r, x, pref[1000005][4], res;
int main() {
	ios_base::sync_with_stdio(0);
	cin >> n >> m;
	while(m--) {
		cin >> l >> r >> x;
		pref[l][x]++;
		pref[r + 1][x]--;
	}
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= 3; j++) {
			pref[i][j] += pref[i - 1][j];
		}

		if(pref[i][1] && pref[i][2] && !pref[i][3]) res++;
	}

	cout << res;
}