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#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define L long long
#define MP make_pair
#define REP(i, n) for(int i = 0; i < n; ++i)
#define REPR(i, n) for(int i = n - 1; i >= 0; --i)
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define FORR(i, a, b) for(int i = b - 1; i >= a; --i)
#define EB emplace_back
#define ST first
#define ND second
#define S size()
#define RS resize

using VI = vector<int>;
using VVI = vector<VI>;
using PI = pair<int, int>;
using VPI = vector<PI>;
using VVPI = vector<VPI>;
using VL = vector<L>;
using VVL = vector<VL>;
using VB = vector<bool>;
using VC = vector<char>;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int n, m;
    cin >> n >> m;
    
    VVI pref(3, VI(n + 2));
    
    REP(i, m)
    {
        int l, r, k;
        cin >> l >> r >> k;
        pref[k - 1][l]++;
        pref[k - 1][r + 1]--;
    }
    
    REP(i, 3)
       FOR(j, 1, n + 2)
           pref[i][j] += pref[i][j - 1];
           
    int wynik = 0;
    FOR(i, 1, n + 1)
       if (pref[0][i] > 0 && pref[1][i] > 0 && pref[2][i] == 0)
           wynik++;
       
    cout << wynik;
}