Playlist Operations

You are given a playlist consisting of several songs, where each song is represented by its duration in seconds. Your task is to implement a Playlist that supports the following operations:

• add X: Add a song with duration X (in seconds) to the end of the playlist.
• remove I: Remove the song at the 0-based index I from the playlist. If I is an invalid index, ignore the operation.
• duration: Output the total duration of all songs currently in the playlist.

The first part of the input provides the initial list of songs. You will then be given a number of operations to perform. For every duration operation, you must print the total duration of the playlist to standard output.

Implementation Details:

• You need to implement a class or structure to handle the playlist operations.
• When removing a song, if the given index is out of bounds, simply ignore the command.

Note: Any mathematical formulas in your explanation should be written in \( \LaTeX \) format.

inputFormat

The input is given in multiple lines:

1. The first line contains an integer N representing the number of songs initially in the playlist.
2. The second line contains N space-separated integers representing the duration (in seconds) of each song. If N is 0, this line may be empty.
3. The third line contains an integer Q representing the number of operations.
4. The following Q lines each contain one operation. Each operation is one of the following:
   • add X — Add a song of duration X seconds.
   • remove I — Remove the song at index I (0-indexed). Ignore if invalid.
   • duration — Output the current total duration of the playlist.

outputFormat

For each duration operation in the input, output the total duration (i.e., the sum of all song lengths in seconds) on a separate line.

## sample

3
120 150 180
5
duration
add 300
duration
remove 1
duration

450
750
600

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