Prove that the continuous $f: \mathbb C \to \mathbb R$ has a global max and min

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I am having this continuous transformation
$f: \mathbb C \to \mathbb R$ and $\ f\ (\mathbb C)$ is bounded Now I have to prove that there are a global maximum and a global minimum.


My thoughts: I think there is a global maximum and a global minimum, because of this theorem:

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Questions: Can I use this for my proof? (I am not sure about the "compactness")