import java.util.*; public class Main { public static int solution(int[] arr) { int length = 0; for(int i = 0 ; i < arr.length ; i++){ int max = Integer.MIN_VALUE; int min = Integer.MAX_VALUE; //HS to check duplicacy HashSet<Integer> set = new HashSet<>(); for(int j =i ; j < arr.length ;j++ ){ max = Math.max(arr[j],max); min = Math.min(arr[j],min); if(set.contains(arr[j])) break; set.add(arr[j]); //contiguous element trick int val1 = max - min; int val2 = j-i; if(val1 == val2){ int potential = j -i +1; if(length < potential) length = potential; } //if max - min becomes more than no.of indexes break; if(val1 > arr.length)break; } } return length; } public static void main(String[] args) { Scanner scn = new Scanner(System.in); int[] arr = new int[scn.nextInt()]; for (int i = 0; i < arr.length; i++) { arr[i] = scn.nextInt(); } System.out.println(solution(arr)); } }