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#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#ifdef LOC
#include "debuglib.h"
#else
#define deb(...)
#define DBP(...)
#endif
using namespace std;
using   ll         = long long;
using   Vi         = vector<int>;
using   Pii        = pair<int, int>;
#define pb           push_back
#define mp           make_pair
#define x            first
#define y            second
#define rep(i, b, e) for (int i = (b); i < (e); i++)
#define each(a, x)   for (auto& a : (x))
#define all(x)       (x).begin(), (x).end()
#define sz(x)        int((x).size())

int main() {
	cin.sync_with_stdio(0); cin.tie(0);
	cout << fixed << setprecision(10);

	int n, m; cin >> n >> m;
	vector<array<int, 3>> ops(n+1);

	rep(i, 0, m) {
		int l, r, k; cin >> l >> r >> k;
		l--; r--; k--;
		ops[l][k]++;
		ops[r+1][k]--;
	}

	int cnt[3] = {};
	int ans = 0;

	rep(i, 0, n) {
		rep(j, 0, 3) cnt[j] += ops[i][j];
		ans += (cnt[0] > 0 && cnt[1] > 0 && cnt[2] == 0);
	}

	cout << ans << '\n';
	return 0;
}