Need formula to report median of last three numbers in a list that will change over time.

[stiga00]

Alright everyone. I need help writing a formula to give back the median for a set of numbers in a list. But the list will grow over time and need the formula to report back the new median each time. But I just need the median of the last three entries. So if the column data was 3, 4, 5. I want it to report back 4. but when I add a 6 in the next row I need it to report back 5 which would be the new median. attached is a sample of what the data will look like in the spreedsheet. Thanks so much