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#include <iostream>
#include <vector>

using namespace std;

int main(){
	int n, m;
	cin >> n >> m;
	vector <bool[3]> tab(n);
	int a, b, c;
	while (m--) {
		cin >> a >> b >> c;
		c--;
		for (int i = a - 1; i < b; i++) tab[i][c] = true;
	}
	c = 0;
	for (auto &i : tab) if (i[0] && i[1] && !i[2]) c++;
	cout << c;
	return 0;
}