# Write a Python Set difference to find lost element from a duplicated array # Function to find lost element from a duplicate# array  def lostElement(A,B):           # convert lists into set     A = set(A)     B = set(B)       # take difference of greater set with smaller     if len(A) > len(B):         print (list(A-B))     else:         print (list(B-A))  # Driver programif __name__ == "__main__":    A = [1, 4, 5, 7, 9]    B = [4, 5, 7, 9]    lostElement(A,B)