import java.util.Scanner;

public class Main{
    static final int N = 100010;
    static int[] q = new int[N];
    static int[] s = new int[N];

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for(int i = 0; i < n; i++) q[i] = sc.nextInt();

        int res = 0;
        for(int i = 0, j = 0; i < n; i++){
            s[q[i]]++;
            while(j < i && s[q[i]] > 1) s[q[j++]]--;
            res = Math.max(res, i - j + 1);
        }

        System.out.println(res);
    }
}