Consider the following statements regarding the Greek and Sunga rule in Punjab:

1. Pushyamitra Sunga, who overthrew the Mauryas, extended his rule over parts of Punjab.

2. King Menander (Milinda), a Greek ruler, is famous for his discussions with Buddhist monk Nagasena, recorded in ‘Milindapanha.’

3. The Sunga dynasty completely expelled the Greeks from Punjab, reestablishing Hindu dominance.

4. The Greeks introduced the die-struck coinage system in Punjab, which influenced later Indian rulers.

How many of the above statements are correct?