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#include <iostream>
#include <set>
#include <vector>
#include <utility>
#include <map>
#include <queue>
#include <algorithm>
#include <string>
using namespace std;
#define PB push_back
#define MP make_pair
#define F first
#define S second
typedef long long ll;
typedef pair<int, int> pii;
const int INF = 1e9;

int n, m;

vector<vector<int>> plusminus;

void solve() {
    cin >> n >> m;
    plusminus.resize(n + 1, {0, 0, 0});
    
    int a, b, c, value;
    for (int i = 0; i < m; i++) {
        cin >> a >> b >> c;
        plusminus[a][c - 1] ++;
        if (b + 1 <= n) {
            plusminus[b + 1][c - 1]--;
        }
    }

    int cnt = 0;
    for (int i = 1; i <= n; i++) {
        plusminus[i][0] += plusminus[i - 1][0];
        plusminus[i][1] += plusminus[i - 1][1];
        plusminus[i][2] += plusminus[i - 1][2];
        
        if (plusminus[i][0] && plusminus[i][1] && !plusminus[i][2]) {
            cnt++;
        }
    }

    cout << cnt << endl;
}


int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);

    solve();

    return 0;
}