#include<iostream>
using namespace std;

long long n, m, item, lhs, rhs, cnt, a[1000001][3];

int main(){
	cin >> n >> m;
	while (m --){
		cin >> lhs >> rhs >> item; item --;
		a[lhs][item] ++;
		a[rhs+1][item] --;
	}
	for (int i=1; i<=n; i++){
		a[i][0] += a[i-1][0];
		a[i][1] += a[i-1][1];
		a[i][2] += a[i-1][2];
		cnt += (     a[i][0]
			and  a[i][1]
			and !a[i][2]
                       );
	}
	cout << cnt;
}