#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int,int> pii;
typedef vector<int> vii;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef unordered_map<int,int> umap;
typedef long double ld;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define popcount __builtin_popcount
#define case cout<<"Case "<<__testcase-testcase<<": ";
#define endl '\n'
#define inf 1e9

ll a[100500];
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int testcase=1;
    //cin>>testcase;
    int __testcase=testcase;
    while(testcase--){
        int n;
        cin>>n;
        int mx=1,cnt=1;
        for(int i=0;i<n-1;i++){
            cin>>a[i];
            if(i==0)a[i]=1;
            if(a[i]==0)
            {
                mx=max(mx,2);
                cnt++;
            }
            else
            {
                mx=max(mx,cnt);
                cnt=1;
            }
        }
        cout<<mx<<endl;

    }
}