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#include<bits/stdc++.h>
using namespace std;
 
#define REP(i, n) for(int i = 0; i < n; i++)
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define ST first
#define ND second
 
ostream& operator<<(ostream &out, string str) {
	for(char c : str) out << c;
	return out;
}
 
template<class L, class R> ostream& operator<<(ostream &out, pair<L, R> p) {
	return out << "(" << p.ST << ", " << p.ND << ")";
}

template<class T> auto operator<<(ostream &out, T &&x) -> decltype(x.begin(), out) {
	out << '{';
	for(auto &e : x)
        	out << e << (&e == &*--x.end() ? "" : ", ");
	return out << '}';
}

template<class... Args> void dump(Args&&... args) {
	((cerr << args << ";  "), ...);
}
 
#ifdef DEBUG
#  define debug(x...) cerr << "[" #x "]: ", dump(x), cerr << "\n"
#else
#  define debug(...) false
#endif
 
template<class T> int size(T && a) { return (int) a.size(); }
 
using LL = long long;
using PII = pair<int, int>;

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

	int n, m;
	cin >> n >> m;
	vector rgb(3, vector<int>(n + 1));
	REP(i, m) {
		int l, r, k;
		cin >> l >> r >> k;
		rgb[k - 1][l - 1]++;
		rgb[k - 1][r]--;
	}

	REP(i, n) REP(j, 3)
		rgb[j][i + 1] += rgb[j][i];	

	int ans = 0;
	REP(i, n)
		if(rgb[0][i] && rgb[1][i] && !rgb[2][i])
			ans++;

	cout << ans << "\n";
}