class Solution {
    public int minOperations(int[] nums1, int[] nums2) {
        if (nums1.length > nums2.length * 6 ||
            nums2.length > nums1.length * 6) {
            return -1;
        }
        int sum1 = 0;
        int sum2 = 0;
        for (int x : nums1) sum1 += x;
        for (int x : nums2) sum2 += x;

        if (sum1 > sum2) { // swap(nums1, nums2) and swap(sum1, sum2)
            int[] temp = nums1; nums1 = nums2; nums2 = temp;
            int tempSum = sum1; sum1 = sum2; sum2 = tempSum;
        } // Make sure that nums1 and nums2 are so that sum1 < sum2

        PriorityQueue<Integer> pq1 = new PriorityQueue<>(); // default ordering, small -> large
        PriorityQueue<Integer> pq2 = new PriorityQueue<>(Collections.reverseOrder()); // large -> small
        for (int x : nums1) pq1.offer(x);
        for (int x : nums2) pq2.offer(x);

        int operations = 0;
        for (; sum1 < sum2; operations++) {
            if (pq2.isEmpty() || pq2.peek() - 1 < 6 - pq1.peek()) {
                // if (it is best to increase the smallest number from nums1)
                sum1 += 6 - pq1.poll();
            } else {
                // else (it is best to decrease the largest number from nums2)
                sum2 -= pq2.poll() - 1;
            }
        }
        return operations;
    }
}