كَمْ رِجَالٍ لَقِيتُهُمْ! — How many men I have met!
كَمْ: declarative noun of quantity, in the nominative position as a topic.
رِجَالٍ: plural genitive tamyīz.
لَقِيتُ: past verb with first-person subject tāʾ.
هُمْ: accusative object pronoun referring back to the men; the verbal clause is the predicate.
The source deliberately illustrates that declarative kam can take a plural tamyīz.