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#include <bits/stdc++.h>
 
#define st first
#define nd second
#define pb push_back
#define BOOST ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
#define PI 3.14159265359
 
using namespace std;
 
typedef long long ll;
constexpr ll MOD = 1000000007, hot = 29;
constexpr ll FOX = 1234567891, cute = 1007;
constexpr ll MEGAN = 1000000009, liv = 107;
constexpr int MXN = 1000000+7 + 10, CZAPA = (1<<20), INF = 1000000000;

vector<int> V[MXN][3];

int main(){	
	BOOST;

	int n, m;
	cin>> n >> m;
	while(m--){
		int p, q, c;
		cin>> p >> q >> c;
		V[p][0].pb(c);
		V[q][1].pb(c);
	}
	// yellow blue red
	int yellow = 0, blue = 0, red = 0, ans = 0;
	for(int i=1; i<=n; i++){
		for(int j : V[i][0]){
			if(j == 1) yellow++;
			else if(j == 2) blue++;
			else if(j == 3) red++;
		}
		if(red == 0 && yellow > 0 && blue > 0)
			ans++;
		for(int j : V[i][1]){
			if(j == 1) yellow--;
			else if(j == 2) blue--;
			else if(j == 3) red--;
		}
	}
	cout<< ans << '\n';
	
	
	return 0;
}