#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) ((int)a.size())
const int mod = 998244353, N = 100007;

int main() {
	ios::sync_with_stdio(false), cin.tie(0);
	int n;
	cin >> n, --n;
	vector <int> a(n);
	for (int i = 0; i < n; ++i) {
		cin >> a[i];
	}
	a[0] = 1;
	int ans = 0;
	for (int i = 0, j = 0; i < n; i = j) {
		while (j < n && a[i] == a[j]) {
			j++;
		}
		if (a[i] == 0) {
			ans = max(ans, j - i);
		}
	}
	cout << ans + 1 << '\n';
}