Oh … kay.
What does 'take an input" mean? Do you have four buttons? Do you want some sort of display showing which buttons were pressed? Will you want some way to clear the queue and start again if the person hits the wrong buttons? Are there rules about what combinations a person can pick (eg: can't pick shampoo twice in a row)?
When the sketch "releases the selected input to the output", is that a matter of turning on a digital output? Should it be held high for a period of time, or should it remain high until the "release" button is pressed again?