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#include <bits/stdc++.h>

using namespace std;

#define ALL(x) (x).begin(), (x).end()

template<class C> void mini(C &a5, C b5) { a5 = min(a5, b5); }
template<class C> void maxi(C &a5, C b5) { a5 = max(a5, b5); }

#ifdef LOCAL
const bool debug = true;
#else
const bool debug = false;
#define cerr if (true) {} else cout
#endif

#define int long long
#define double long double

const int INF = 1e18;
const int mod = 1e9 + 7;

const int max_n = 1e6 + 100;

int bar[max_n][5];
int cur[5];

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
		int a, b, c;
		cin >> a >> b >> c;
		bar[a][c]++;
		bar[b + 1][c]--;
	}
	
	int res = 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= 3; j++) {
			cur[j] += bar[i][j];
		}
		
		if (cur[1] && cur[2] && cur[3] == 0) res++;
	}
	cout << res;
    
    return 0;
}/*
9 5
2 8 1
4 5 2
6 7 3
5 6 2
1 2 2
*/