#include <bits/stdc++.h>

const int MAX_N = 1e6;

int t[5][MAX_N+3];

int main() {
    std::ios_base::sync_with_stdio(0); std::cin.tie(NULL);
    int n, m;
    std::cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int l, r; int k;
        std::cin >> l >> r >> k;
        t[k][l]++;
        t[k][r+1]--;
    }
    int res = 0;
    int sum1, sum2, sum3;
    sum1 = sum2 = sum3 = 0;
    for (int i = 1; i <= n; i++) {
        sum1 += t[1][i];
        sum2 += t[2][i];
        sum3 += t[3][i];
        if (sum1 > 0 && sum2 > 0 && sum3 == 0)
            res++;
    }
    std::cout << res << "\n";
}