Given an array `intervals` where `intervals[i] = [li, ri]` represent the interval `[li, ri)`, remove all intervals that are covered by another interval in the list.

The interval `[a, b)` is covered by the interval `[c, d)` if and only if `c <= a` and `b <= d`.

Return _the number of remaining intervals_.

**Example 1:**

**Input:** intervals = \[\[1,4\],\[3,6\],\[2,8\]\]
**Output:** 2
**Explanation:** Interval \[3,6\] is covered by \[2,8\], therefore it is removed.

**Example 2:**

**Input:** intervals = \[\[1,4\],\[2,3\]\]
**Output:** 1

**Constraints:**

*   `1 <= intervals.length <= 1000`
*   `intervals[i].length == 2`
*   `0 <= li < ri <= 105`
*   All the given intervals are **unique**.


def maximum_sum(arr):
    n = len(arr)
    sum_without_deletion = [0] * n
    sum_with_deletion = [0] * n
    sum_without_deletion[0] = arr[0]
    sum_with_deletion[0] = 0
    max_sum = arr[0]

    for i in range(1, n):
        sum_without_deletion[i] = max(arr[i], sum_without_deletion[i - 1] + arr[i])
        sum_with_deletion[i] = max(sum_with_deletion[i - 1] + arr[i], sum_without_deletion[i - 1])
        max_sum = max(max_sum, max(sum_without_deletion[i], sum_with_deletion[i]))
    return max_sum
