#include <bits/stdc++.h>
using namespace std;
int n, m, a, b, cnt[5005], maxCnt;
bool hi[5005], vis[5005];
vector<int> v[5005];
void topSort(int x) {
	queue<int> q;
	q.push(x);
	while (!q.empty()) {
		int u = q.front();
		q.pop();
		for (auto i : v[u]) {
			if (!vis[i]) {
				q.push(i);
				vis[i] = true;
			}
			cnt[i] = (cnt[i] + cnt[u]) % 80112002;
		}
	}
}
int main() {
	cin >> n >> m;
	for (int i = 1; i <= m; i++) {
		cin >> a >> b;
		v[a].push_back(b);
		hi[b] = true;
	}
	for (int x = 1; x <= n; x++) 
		if (!hi[x]) {
			memset(vis, false, sizeof vis);
			cnt[x] = 1;
			topSort(x);
		}
	for (int i = 1; i <= n; i++)
		maxCnt = max(maxCnt, cnt[i]);
	cout << maxCnt;
	return 0;
}