Given below are two pairs of statements. Combine these two statements using ''if and only if ''.
(i) p: If a rectangle is a square, then all its four sides are equal. q: If all the four sides of a rectangle are equal, then the rectangle is a square.
(ii) p: If the sum of digits of a number is divisible by 3, then the number is divisible by 3.
q: If a number is divisible by 3, then the sum of its digits is divisible by 3.