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#include <bits/stdc++.h>
#define PB push_back
#define ST first
#define ND second
#define _ ios_base::sync_with_stdio(0); cin.tie(0);
//mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

using namespace std;

using ll = long long;
using pi = pair<int,int>;
using vi = vector<int>;

const int nax = 1000 * 1000 + 10;
int n, m;
int t[nax][3];
bool col[nax][3];

int main() {_
	cin >> n >> m;
	while(m--) {
		int a, b, k;
		cin >> a >> b >> k;
		k--;
		t[a][k]++;
		t[b + 1][k]--;
	}
	for(int k = 0; k < 3; ++k) {
		int cur = 0;
		for(int i = 1; i <= n; ++i) {
			cur += t[i][k];
			col[i][k] = (cur > 0);
		}
	}
	int ans = 0;
	for(int i = 1; i <= n; ++i) {
		if(col[i][0] && col[i][1] && (!col[i][2])) ans++;
	}
	cout << ans;
	
}