import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		int[] arr = new int[N];
		for(int i = 0; i < N; i++){
			arr[i] = sc.nextInt();
		}
		
		int max = 0;
		Map<Integer, Integer> map = new HashMap<Integer, Integer>();
		
		int left = 0;
		for(int i = 0; i < N; i++){
			if(map.containsKey(arr[i])){
				max = Math.max(max, i - left);
				left = map.get(arr[i]) + 1;
			}
			map.put(arr[i], i);
		}
		max = Math.max(max, N - left);
		
		System.out.println(max);
	}
	
}