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#include <bits/stdc++.h>
using namespace std;

template<typename T>
T load() {
    auto value = T{};
    cin >> value;
    return value;
}

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

    auto n = load<size_t>();
    auto m = load<size_t>();

    auto left_ends = vector<vector<unsigned>>(3, vector<unsigned>(n));
    auto right_ends = vector<vector<unsigned>>(3, vector<unsigned>(n + 1));

    for (size_t i = 0; i < m; i++) {
        auto l = load<size_t>();
        auto r = load<size_t>();
        auto k = load<size_t>();

        left_ends[k - 1][l - 1] += 1;
        right_ends[k - 1][r] += 1;
    }

    auto result = 0;
    auto counter = array<size_t, 3>{0, 0, 0};
    for (auto i = size_t{0}; i < n; i++) {
        for (auto j : {0, 1, 2}) {
            counter[j] += left_ends[j][i];
            counter[j] -= right_ends[j][i];
        }

        if (counter[0] > 0 && counter[1] > 0 && counter[2] == 0) {
            result += 1;
        }
    }

    cout << result << "\n";
}