I just want to show [Second] for timer app on watch complication

I could make countdown on watch complication by using [.timer]. However its showing [Hour], [Minute] and [Second], and I just want to show [Second] instead of [Hour] and [Minute]. Lets say if I set the time with [5 minutes] then I would like to make it showing [300] instead of [5:00]. So what will be the best code I should write? Please kindly advise.