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#include <bits/stdc++.h>

using namespace std;

void solve (int n, int L, vector <vector <bool> >& t, vector <vector <bool> >& tp)
{
	int l, r, k;
	cin >> l >> r >> k;
	--l;
	--k;
	while (l % L != 0 && l < r)
	{
		t[l][k] = true;
		l++;
	}
	while (l + L <= r)
	{
		tp[l/L][k] = true;
		l += L;
	}
	while (l < r)
	{
		t[l][k] = true;
		l++;
	}
}

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

    int n, m;
    cin >> n >> m;
    
    int L = sqrt(n);
    if (L*L != n) ++L;
    
    vector <vector <bool> > t (n+1, vector <bool>(3));
    vector <vector <bool> > tp (L+1, vector <bool>(3));

    while (m--) 
        solve(n, L, t, tp);
        
    int res = 0;
    for (int i = 0; i < n; ++i)
    {
    	if (!t[i][2] && !tp[i/L][2] && (t[i][1] || tp[i/L][1]) && (t[i][0] || tp[i/L][0]))
    		++res;
    }
   
    cout << res;
    return 0;
}