forward a certain time

[zorroislost]

Hey guys pretty straight forward question here. There's lots of sites and apps nowadays with time limits. I would like to cut clips to a specific time duration. There is already a "forward one minute" button on avidemux. Is there a way to change the settings or make a new button/shortcut for "forward specific time".
Right now I am adding 30 secs to my A marker, but I am so bad at fast arithmetic, it takes forever -_-.

Thank you for the time.

[eumagga0x2a]

This is so easy to accomplish using Ctrl+T, setting marker B, saving the video, hitting Delete and repeating these steps that I don't think there is any justification for more buttons or shortcuts.