Given a number 'N'. The task is to find the Nth number whose each digit is a prime number i.e 2, 3, 5, 7. In other words you have to find nth number of this sequence : 2, 3, 5, 7, 22, 23 ,.. and so on.
N = 10
Explanation:10th number in the sequence of
numbers whose each digit is prime is 33.
N = 21
Explanation:21st number in the sequence of
numbers whose each digit is prime is 222.
Complete primeDigits function and return the nth number of the given sequence made of prime digits.