#include <bits/stdc++.h>
using namespace std;
#define fastio (ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL))
typedef long long ll;
typedef long double lld;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
const int MAXSIZE = 2000000;
const long long INF = 1e18 + 5;
const double EPSILON = 1e-14;
const ll DIV = 2000003;
const long double pi = 3.14159265358979323846264338327950288419716939937510L;

int n;
int arr[101010];

int main()
{
    fastio;
    int ans = 1;
    cin >> n;
    int cur = 0;
    for (int i = 1; i < n; i++)
    {
        int a;
        cin >> a;
        if (a == 1)
        {

            cur = 1;
        }
        else
        {
            ans = max(ans, cur + 1);
            cur++;
        }
    }
    cout << ans;
    return 0;
}