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#include <vector>
#include <cstdio>
#include <algorithm>

#define YELLOW 0

using namespace std;

struct Range {
  int start;
  int end;

  Range() { 
    this->start = 1000000000;
    this->end = 1000000000;
  }

  Range(int start, int end) {
    this->start = start;
    this->end = end;
  }
};

bool range_cmp(Range A, Range B) {
  return A.start < B.start;
}

int main() {
  int n, m;

  scanf("%d %d", &n, &m);

  vector<vector<Range>> colors(3);
  vector<vector<bool>> painted(3);

  for (int i=0; i<3; i++) {
    colors[i].resize(m);
    painted[i].resize(n, false);
  }

  int amounts[3] = {0, 0, 0};

  for (int i=0; i<m; i++) {
    int l, r, k;

    scanf("%d %d %d", &l, &r, &k);

    k--;
    l--;
    r--;

    colors[k][amounts[k]] = Range(l, r);
    amounts[k]++;
  }

  for (int i=0; i<3; i++) {
    colors[i].resize(amounts[i]);
    sort(colors[i].begin(), colors[i].end(), range_cmp);
  
    int last_idx = 0;

    for (int j=0; j<colors[i].size(); j++) {
      int start = 1000000000;

      if (last_idx >= colors[i][j].start && last_idx < colors[i][j].end) {
        start = last_idx;
      } else if (last_idx < colors[i][j].start) {
        start = colors[i][j].start;
      }

      for (int k=start; k<=colors[i][j].end; k++) {
        painted[i][k] = true;
        last_idx = k;
      }
    }
  }

  int result = 0;

  for (int i=0; i<n; i++) {
    // printf("%s %s %s\n", painted[0][i]?"true":"false", painted[1][i]?"true":"false", painted[2][i]?"true":"false");
    if (painted[0][i] && painted[1][i] && !painted[2][i]) {
      result++;
    }
  }

  printf("%d", result);
}