Consider the following statements with reference to the procedure of amendment of Indian Constitution:
1. A Bill for the amendment of provisions of Article 368, has to be ratified by not less than half of the states.
2. The power to initiate an amendment to the Constitution lies with the Indian Parliament only.
3. Indian constitution has no provision for holding a joint sitting for the deadlock over the passage of a constitutional amendment bill.
4. According to the Constitution, if a state once approves a Constitutional amendment bill, it cannot withdraw its approval to such a bill.
How many of the statements given above are correct?