Let S={(m, n): m, n ∈ {1, 2, 3, ....., 50}}. If the number of elements (m, n) in S such that 6^m + 9ⁿ is a multiple of 5 is p and the number of elements (m, n) in S such that m + n is a square of a prime number is q, then p + q is equal to……..