#include<bits/stdc++.h> using namespace std; #define int long long #define INF 0x3f3f3f3f3f3f3f3f int n,m,ma=-INF; int a[1010]; signed main(){ freopen("competition.in","r",stdin); freopen("competition.out","w",stdout); cin>>n; for(int i=1;i<=n;i++) { cin>>a[i]; m++; if(a[i]==1) { ma=max(ma,m); m=0; } } cout<<ma; return 0; }