6. (Check SSN) Write a C++ program that prompts the user to enter a Social Security Number in the format ddd-dd-dddd, where d is a digit and check the validity of the SSN (The input may contain either digit or dash and conforms to the mentioned format). Here are sample runs: Enter a SSN: 232-23-4532 232234532 is valid Enter a SSN: 32-123-4532 321234532 is invalid