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#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;


vector<int> Red;
vector<int> Yellow;
vector<int> Blue;

vector<int> tab[3];

int n, m;

void add(vector<int>& v, int start, int end){
	int index = lower_bound(v.begin(), v.end(), start) - v.begin();
	
	if (v.size() == 0){
		v.push_back(start);
		v.push_back(end);
		return;
	}
	
	if (index % 2 == 1);
	else if (index == 0){
		v.insert(v.begin(), start);
		index++;
	}
	else if (v[index - 1] == start - 1){
		v.erase(v.begin() + index - 1);
		index--;
	}
	else {
		if (index == v.size()) v.push_back(start);
		else v.insert(v.begin() + index, start);
		index++;
	}
	
	int d = v.size();
	while (index < d){
		if (v[index] <= end){
			v.erase(v.begin() + index);
			d -= 1;
		}
		else break;
	}
	
	
	
	if (index == v.size()) v.push_back(end);
	else if (v.size() % 2 == 1 && v[index] <= end + 1) v.erase(v.begin() + index);
	else if (v.size() % 2 == 1) v.insert(v.begin() + index, end);
	
}

int main() {
	
	tab[0] = Yellow;
	tab[1] = Blue;
	tab[2] = Red;
	
	cin >> n; 
	cin >> m;
	
	int s, e, t;
	for (int i = 0; i < m; i++){
		cin >> s >> e >> t;
		add(tab[t - 1], s, e);
	} 
	
	
	vector<int> Green;
	int counter = 0;
	int NS;
	int NE;
	int i1 = 0;
	int i2 = 0;
	bool b = true;
	
	int start;
	int end;
	
	while (i1 < tab[0].size()){
		NS = tab[0][i1];
		NE = tab[0][i1 + 1];
		i1 += 2;
		while (tab[1][i2] <= NE && i2 < tab[1].size()){
			start = max(NS, tab[1][i2]);
			end = min(NE, tab[1][i2 + 1]);
			Green.push_back(start);	
			Green.push_back(end);
			counter += max(0, end - start + 1);
			i2 += 2;
		}
		i2 -= 2;
		i2 = max(0, i2);
	}
	
	if (tab[2].size() == 0) {
		cout << counter;
		return 0;
	}
	
	i1 = 0;
	i2 = 0;
	b = true;
	while (i1 < Green.size()){
		NS = Green[i1];
		NE = Green[i1 + 1];
		i1 += 2;
		while (tab[2][i2] <= NE && i2 < tab[2].size()){
			start = max(NS, tab[2][i2]);
			end = min(NE, tab[2][i2 + 1]);
			counter -= max(0, end - start + 1);
			i2 += 2;
		}
		i2 -= 2;
		i2 = max(i2, 0);
	}
	
	cout << counter;
	
	return 0;
}