Counting morphisms between specified groups

Determine the number of group homomorphisms ϕ between the given groups. Here K4 denotes the Klein four-group (also known as Z/2Z×Z/2Z) and S3 denotes the symmetric group on three elements.

  1. ϕ:K4Z/2Z
  2. ϕ:Z/2ZK4
  3. ϕ:S3K4
  4. ϕ:K4S3