Two natural numbers n and d (with 0 <= d <= 9) are read. Print how many times the digit d appears in the decimal representation of n, using a recursive function.
Define a recursive function count(n, d) that returns the number of occurrences of digit d in n:
count(0, d) = 0
count(n, d) = (n % 10 == d ? 1 : 0) + count(n / 10, d), for n > 0Special case n == 0: if d == 0, the answer is 1 (the number 0 has one digit, which is 0); otherwise the answer is 0.