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#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <set>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <unordered_map>
using namespace std;

typedef long long int LL;
typedef long double LD;
typedef vector<int> VI;
typedef vector<LL> VLL;
typedef vector<LD> VLD;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef vector<PII> VPII;

const int INF = 1000000001;
const LD EPS = 10e-9;

#define FOR(x, b, e) for(int x = b; x <= (e); ++x)
#define FORD(x, b, e) for(int x = b; x >= (e); --x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define MP make_pair
#define PB push_back
#define ST first
#define ND second
#define abs(a) ((a)<0 ? -(a) : (a))
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))

bool compare(const pair<int, int>& a, const pair<int, int>& b)
{
    if(a.first == b.first)
    {
        return a.second > b.second;
    }
    return a.first < b.first;
}

const int MAX_N = 1000005;

int n, m;
int l, r, k, res;
bool yellow[MAX_N], blue[MAX_N], red[MAX_N];
vector<pair<int, int>> yellowPoints, bluePoints, redPoints;

bool* gridArrayFor(const int color)
{
    if(color == 1)
    {
        return yellow;
    }
    if(color == 2)
    {
        return blue;
    }
    return red;
}

vector<pair<int, int>>& pointsVectorFor(const int color)
{
    if(color == 1)
    {
        return yellowPoints;
    }
    if(color == 2)
    {
        return bluePoints;
    }
    return redPoints;
}

int counter2;

void setTrue(const int color, const int left, const int right)
{
    auto* gridArray = gridArrayFor(color);
    fill(gridArray+left, gridArray+right+1, true);
}

int counter;

void computeGrid(const int color)
{
    auto& pointsVector = pointsVectorFor(color);
    auto* gridArray = gridArrayFor(color);

    int layers = 0, left = 0, right = 0;
    for(const auto& elem : pointsVector)
    {
        layers += elem.second;

        if(layers == 1 && elem.second == 1)
        {
            left = elem.first;
        }
        else if(layers == 0 && elem.second == -1)
        {
            right = elem.first;

            setTrue(color, left, right);
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(0);

    cin >> n >> m;
    for(int i = 0; i < m; ++i)
    {
        cin >> l >> r >> k;

        const auto start = make_pair(l, 1);
        const auto end = make_pair(r, -1);

        auto& vectorToFill = pointsVectorFor(k);
        vectorToFill.push_back(start);
        vectorToFill.push_back(end);
    }

    for(int i = 1; i <= 3; ++i)
    {
        auto& vectorToSort = pointsVectorFor(i);
        sort(vectorToSort.begin(), vectorToSort.end(), compare);

        computeGrid(i);
    }

    /*cout << endl;
    for(int i = 1; i <= 3; ++i)
    {
        auto* gridArray = gridArrayFor(i);
        for(int j = 1; j <= n; ++j)
        {
            cout << gridArray[j] << ' ';
        }
        cout << endl;
    }
    cout << endl;*/

    for(int i = 1; i <= n; ++i)
    {
        if(yellow[i] && blue[i] && !red[i])
        {
            ++res;
        }
    }

    cout << res << endl;

    return 0;
}