3986. Number of Elapsed Seconds Between Two Times

You are given two valid times startTime and endTime, each represented as a string in the format "HH:MM:SS".

Return the number of seconds that have elapsed from startTime to endTime.

Example 1:

Example 2:

Constraints:

• startTime.length == 8
• endTime.length == 8
• startTime and endTime are valid times in the format "HH:MM:SS"
• 00 <= HH <= 23
• 00 <= MM <= 59
• 00 <= SS <= 59
• endTime is not earlier than startTime