  We study general teleportation scheme with an arbitrary state of the pair of
particles (2 and 3) shared by Alice and Bob, and arbitrary measurements on the
input particle 1 and one of the members (2) of the pair on Alice's side. We
find an efficient iterative algorithm for identifying optimum local operations
on Bob's side. In particular we find that simple unitary transformations on his
side are not always optimal even if particles 2 and 3 are perfectly entangled.
We describe the most interesting protocols in the language of extremal
completely-positive maps.
