Median value of two same-length sorted lists

mediane.py

# Returns the two median values of two same-length sorted lists
# Algorithm complexity: O(lg n), n being the length of the lists

# Usage: mediane.py [firstlist] [secondlist]
# Input lists as integers separated by spaces (wrap list in quotemarks to input it as one command line argument)

import math, sys

def mediane(X, Y):
  n = len(X)
  if n == 2:
    T = X + Y
    del(T[T.index(min(T))])
    del(T[T.index(max(T))])
    return T
  else:
    pivot = math.ceil((n-1)/2)
    if X[pivot] < Y[pivot]:
      X = X[math.floor((n-1)/2):]
      Y = Y[:math.floor(n/2)+1]
    else:
      X = X[:math.floor(n/2)+1]
      Y = Y[math.floor((n-1)/2):]
    return mediane(X, Y)

def main(argv):
  X = argv[0].split(" ")
  Y = argv[1].split(" ")
  for i in range(len(X)):
    X[i] = int(X[i])
    Y[i] = int(Y[i])
  print (mediane(X, Y))

if __name__ == "__main__":
   main(sys.argv[1:])