Think my math is wrong?

[buran]

// is floor division:

>>> 5//2
2

so if there are odd number of elements you want to return srt[mid+1] (on line 6)

With even number of elements median should be the mean of the middle two numbers (i.e. the true division of the middle 2 elements)- mid and mid+1, not mid-1
med = (srt[mid] + srt[mid+1]) / 2

Also because of using floor division you don't need to explicitly convert to int on line 8 (but this is just a note)

that said, you better add argument to median function, instead of using global variable lst