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#include <iostream>
#include <string>
#include <list>
#include <algorithm>
#include <vector>

using namespace std;

class Span
{
public:
	int beg;
	int end;
	Span(int i, int j) : beg(i), end(j) {}
};

class Ranges
{
public:

	list<Span> spans;

	void add(int beg, int end)
	{
		auto i = spans.begin();
		bool extend = false;
		auto extended = spans.begin();
		while (i != spans.end())
		{
			if (extend)
			{
				if (end > i->end)
				{
					auto j = i;
					i++;
					spans.erase(j);
					continue;
				}
				if (end < i->beg - 1)
				{
					extended->end = end;
					return;
				}
				extended->end = i->end;
				spans.erase(i);
				return;
			}
			if (beg > i->end + 1)
			{
				i++;
				continue;
			}
			if (end < i->beg - 1)
			{
				spans.insert(i, Span(beg, end));
				return;
			}
			if (beg < i->beg)
			{
				i->beg = beg;
			}
			if (end <= i->end)
			{
				return;
			}
			if (end > i->end)
			{
				extend = true;
				extended = i;
			}
			else
			{
				return;
			}
			i++;
		}
		if (extend)
		{
			extended->end = end;
		}
		else
		{
			spans.push_back(Span(beg, end));
		}
	}
};

int main()
{
	int n, m;
	std::cin >> n >> m;
	Ranges colors[3];
	vector<bool> v1(n);
	vector<bool> v2(n);
	vector<bool> v3(n);
	vector<vector<bool>> v{ v1, v2, v3 };

	int l, r, k;
	while (m > 0)
	{
		std::cin >> l >> r >> k;
		k--;
		if (r - l > 706)
		{
			colors[k].add(l, r);
		}
		else
		{
			for (int i = l; i <= r; i++)
			{
				v[k][i] = true;
			}
		}
		m--;
	}

	for (int c = 0; c < 3; c++)
	{
		auto i = colors[c].spans.begin();
		while (i != colors[c].spans.end())
		{
			for (int j = i->beg; j <= i->end; j++)
			{
				v[c][j] = true;
			}
			i++;
		}
	}

	for (int i = 0;  i < n; i++)
	{
		v[0][i] = v[0][i] && v[1][i];
	}

	int green = 0;
	for (int i = 0; i < n; i++)
	{
		if (v[0][i] && !v[2][i])
		{
			green++;
		}
	}

	cout << green;
	return 0;
}