Directions for the following two questions:
Let \( S \) be the set of all pairs \( (i, j) \) where \( 1 \leq i < j \leq n \), and \( n \geq 4 \) (\( i \) and \( j \) are natural numbers). Any two distinct members of \( S \) are called “friends” if they have one constituent of the pairs in common and “enemies” otherwise.
For example, if \( n = 4 \), then \( S = \{(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)\} \). Here, \( (1, 2) \) and \( (1, 3) \) are friends, \( (1,2) \) and \( (2, 3) \) are also friends, but \( (1,4) \) and \( (2, 3) \) are enemies.