#include <bits/stdc++.h>
#define F first
#define S second

using namespace std;

int n;
int arr[1000005];
int dp[1000005] = {0};
const int N = 1e6 + 5;

signed main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int mx = 0, cur = 0;
    cin >> n;
    int get0 = 0;
    for (int i = 1; i < n; i++) {
        cin >> arr[i];
        if (i == 1)
            ;
        else if (!arr[i]) {
            cur++;
            mx = max(cur, mx);
        } else {
            mx = max(cur, mx);
            cur = 0;
        }
    }
    cout << mx + 1;
    return 0;
}