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#include "bits/stdc++.h" // Tomasz Nowak
using namespace std;     // XIII LO Szczecin
using LL = long long;    // Poland
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
template<class T> int size(T &&x) {
	return int(x.size());
}
template<class A, class B> ostream& operator<<(ostream &out, const pair<A, B> &p) {
	return out << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &out, T &&x) -> decltype(x.begin(), out) {
	out << '{';
	for(auto it = x.begin(); it != x.end(); ++it)
		out << *it << (it == prev(x.end()) ? "" : ", ");
	return out << '}';
}
void dump() {}
template<class T, class... Args> void dump(T &&x, Args... args) {
	cerr << x << ";  ";
	dump(args...);
}
#ifdef DEBUG
  struct Nl{~Nl(){cerr << '\n';}};
# define debug(x...) cerr << (strcmp(#x, "") ? #x ":  " : ""), dump(x), Nl(), cerr << ""
#else
# define debug(...) 0 && cerr
#endif
mt19937_64 rng(0);
int rd(int l, int r) {
	return uniform_int_distribution<int>(l, r)(rng);
}
// end of templates

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

	int n, m;
	cin >> n >> m;

	constexpr int colors = 3;
	array<vector<int>, colors> pref;
	for(auto &vec : pref)
		vec.resize(n + 1);

	while(m --> 0) {
		int l, r, k;
		cin >> l >> r >> k;
		--l, --r, --k;
		++pref[k][l];
		--pref[k][r + 1];
	}
	debug(pref);

	REP(c, colors)
		FOR(i, 1, n - 1)
			pref[c][i] += pref[c][i - 1];
	debug(pref);

	int ans = 0;
	REP(i, n)
		if(pref[0][i] > 0 and pref[1][i] > 0 and pref[2][i] == 0)
			++ans;
	cout << ans << '\n';
}