import java.util.ArrayList;
import java.util.Scanner;

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

        ArrayList<Integer> list = new ArrayList<>();
        int prev = a[0];
        int count = 0;
        for (int i : a) {
            if (i == prev) {
                count++;
            } else {
                list.add(count);
                count = 1;
                prev = i;
            }
        }
        list.add(count);

//        for (int i = 0; i < list.size(); i++) {
//            System.out.print(list.get(i)+" ");
//        }
//        System.out.println();

        long[][] dp = new long[list.size() + 10][2];
        dp[0][0] = 0;
        dp[0][1] = 0;

        for (int i = 1; i <= list.size(); i++) {
            dp[i][0] = Math.max(dp[i - 1][0], dp[i - 1][1]);
            dp[i][1] = dp[i - 1][0] + list.get(i - 1);
        }

        System.out.println(Math.max(dp[list.size()][0], dp[list.size()][1]));
    }
}