Untitled

import java.util.*;

public class Solution {
    public static int solve(int N, List<Integer> A) {
        // Convert List to array for easier handling
        int[] nums = A.stream().mapToInt(i -> i).toArray();

        // Initialize variables
        HashMap<Integer, Integer> map = new HashMap<>();
        map.put(0, -1);
        int maxLength = -1;
        int count = 0;

        // Iterate through the array
        for (int i = 0; i < nums.length; i++) {
            // Adjust the count based on the value
            count += (nums[i] == 1) ? 1 : -1;

            // Check if this count has been seen before
            if (map.containsKey(count)) {
                // Update the maximum length if this subarray is longer
                maxLength = Math.max(maxLength, i - map.get(count));
            } else {
                // Store the first occurrence of this count
                map.put(count, i);
            }
        }

        // If no subarray was found, return -1
        return (maxLength == 0) ? -1 : maxLength;
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int N = Integer.parseInt(scan.nextLine().trim());

        List<Integer> A = new ArrayList<>(N);
        for (int j = 0; j < N; j++) {
            A.add(Integer.parseInt(scan.nextLine().trim()));
        }

        int result = solve(N, A);
        System.out.println(result);
    }
}