#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>

using namespace std;

int n, seg;
vector <pair<int, int> > yellow;

vector <pair<int, int> > blue;
vector <pair<int, int> > red;

int a, b, c;
int tab[1000100];
int main() {
   
    cin.tie(0);cout.tie(0);
    ios_base::sync_with_stdio(0);

    cin >> n >> seg;
    for(int i = 0; i < seg; i++){
        cin >> a >> b >> c;
        if(c == 1){
            yellow.push_back(make_pair(a,b));
        }
        else if(c == 2){
            blue.push_back(make_pair(a,b));
        }
        else{
            red.push_back(make_pair(a,b));
        }
    }
    sort(yellow.begin(), yellow.end());
    sort(blue.begin(), blue.end());
    sort(red.begin(), red.end());

    //yellow
    int current = 0;
    int ind = 0;
    while(current < yellow.size()){
        for(int i = max(ind, yellow[current].first); i <= yellow[current].second; i++){
            tab[i] |= 1;
        }
        ind = max(ind, yellow[current].second);
        current++;
    }
    /*
    for(int i = 1; i <= n; i++){
        cout << tab[i] << " ";
    }
    return 0;*/
    //blue
    current = 0;
    ind = 0;
    while(current < blue.size()){
        for(int i = max(ind, blue[current].first); i <= blue[current].second; i++){
            tab[i] |= 2;
        }
        ind = max(ind, blue[current].second);
        current++;
    }
    //red
    current = 0;
    ind = 0;
    while(current < red.size()){
        for(int i = max(ind, red[current].first); i <= red[current].second; i++){
            tab[i] |= 4;
        }
        ind = max(ind, red[current].second);
        current++;
    }

    //final check
    int green = 0;
    for(int i = 1; i <= n; i++){
        if(tab[i] == 3)
            green++;
    }
    cout << green;
    return 0;
}