import java.util.*; public class Main { public static int solution(int[] arr){ int j = 0 , count = 0 , ans = 0; //acquiring loop for(int i = 0 ; i < arr.length ; i++){ if(arr[i] == 0) count++; //releasing loop till count becomes valid again while(count > 1){ if(arr[j] == 0) count--; j++; } //update answer int len = i - j + 1; ans = Math.max(len , ans); } return ans; } public static void main(String[] args) { Scanner scn = new Scanner(System.in); int n = scn.nextInt(); int[] arr = new int[n]; for(int i = 0 ; i < n; i++){ arr[i] = scn.nextInt(); } System.out.println(solution(arr)); } }