#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define ld long double
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pdd pair<ld, ld>
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second

const int NMAX = 100005;
const int inf = 1 << 30;

int n, m, cnt, X[NMAX], Y[NMAX], Z[NMAX];
int tsort[NMAX], comp[NMAX], mlc[NMAX], d[NMAX];
int is[NMAX], bun[NMAX];

vector<pii> v[NMAX], g[NMAX];
vector<int> C[NMAX], V[NMAX];
bitset<NMAX> viz, inq;
deque<int> q;

void dfs(int x) {
	viz[x] = 1;

	for (auto it : v[x])
		if (!viz[it.fi])
			dfs(it.fi);

	tsort[++cnt] = x;
}

void dfst(int x) {
	C[cnt].pb(x);
	comp[x] = cnt;
	viz[x] = 1;

	for (auto it : g[x])
		if (!viz[it.fi])
			dfst(it.fi);
}

int bf(int source, int where) {
	for (auto it : C[where])
		d[it] = inf, inq[it] = 0, mlc[it] = 0;

	q.clear();
	d[source] = 0;
	q.pb(source);
	inq[source] = 1;

	while (!q.empty()) {
		int x = q.front();
		q.pop_front();
		inq[x] = 0;

		mlc[x]++;
		if (mlc[x] == (int)C[where].size() + 1)
			return 1;

		for (auto it : v[x])
			if (comp[it.fi] == where && d[x] + it.se < d[it.fi]) {
				d[it.fi] = d[x] + it.se;
				if (!inq[it.fi]) {
					inq[it.fi] = 1;
					q.pb(it.fi);
				}
			}
	}

	return 0;
}

void go(int x) {
	bun[x] = is[x];
	viz[x] = 1;

	for (auto it : V[x])
		if (!viz[it]) {
			go(it);
			bun[x] |= bun[it];
		}
}

int main() {
	cin.sync_with_stdio(false);

	cin >> n >> m;
	for (int i = 1; i <= m; i++) {
		cin >> X[i] >> Y[i] >> Z[i];
		v[X[i]].pb(mp(Y[i], Z[i]));
		g[Y[i]].pb(mp(X[i], Z[i]));
	}

	for (int i = 1; i <= n; i++)
		if (!viz[i])
			dfs(i);

	viz = 0;
	cnt = 0;

	for (int i = n; i; i--) {
		int x = tsort[i];
		if (!viz[x])
			cnt++, dfst(x);
	}

	for (int i = 1; i <= m; i++)
		V[comp[X[i]]].pb(comp[Y[i]]);

	for (int i = 1; i <= cnt; i++) {
		sort(all(V[i]));
		V[i].resize(unique(V[i].begin(), V[i].end()) - V[i].begin());
	}

	for (int i = 1; i <= cnt; i++)
		is[i] = bf(C[i][0], i);

	viz = 0;
	for (int i = 1; i <= cnt; i++)
		if (!viz[i])
			go(i);

	int SOL = 0;
	for (int i = 1; i <= cnt; i++)
		if (bun[i])
			SOL += (int)C[i].size();

	cout << SOL;

	return 0;
}