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

struct Point {
    int pos;
    int col;
    int count;
    bool operator<(Point const& p) {
        return pos < p.pos;
    }
};

int main() {
    std::ios::sync_with_stdio(false);

    int n, m;
    std::cin >> n >> m;
    std::vector<Point> v;
    for (int i = 0; i < m; ++i) {
        int l, r, k;
        std::cin >> l >> r >> k;
        v.push_back({l - 1, k - 1, 1});
        v.push_back({r, k - 1, -1});
    }
    std::sort(v.begin(), v.end());

    std::vector<int> counts(3);
    auto it = v.begin();

    int ret = 0;

    for (int i = 0; i < n; ++i) {
        while (it != v.end() && it->pos <= i) {
            counts[it->col] += it->count;
            it++;
        }
        if (counts[0] > 0 && counts[1] > 0 && counts[2] == 0) {
            ret++;
        }
    }

    std::cout << ret;

    return 0;
}