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#include <ctime>
#include <cassert>
#include <iostream>
#include <cstdio>
#include <iomanip>
#include <vector>
#include <algorithm>
using namespace std;
const int MAXN = 1000000;
const int MAXM = 1000000;

#define FOR(i, n) for(int i = 0, __n = (n); i < __n; i++)



int p[MAXN+1][3];

int main() {
  // ios_base::sync_with_stdio(0);
  int n, m;
  // cin >> n >> m;
  scanf("%d%d", &n, &m);
  // FOR (i, n+1) FOR (j, 3) p[i][j] = 0;

  FOR (i, m) {
    int l, r, k;
    // cin >> l >> r >> k;
    scanf("%d%d%d", &l, &r, &k);

    p[l-1][k-1]++;
    p[r][k-1]--;

  }

  int sum = 0;
  int s[3] = {0, 0, 0};

  FOR (i, n) {
    FOR (j, 3) s[j] += p[i][j];
    // cerr << !!s[0] << !!s[1] << !!s[2] << endl;
    if (s[0] > 0 && s[1] > 0 && s[2] == 0) {
      sum++;
    }
  }
  cout << sum << endl;

  return 0;
}