Let \( A = \{4, 5, 7\} \) and \( B = \{2, 4, 6\} \) be two sets and let \( R \) be a relation from \( A \) to \( B \) defined by \( R : \{(x, y) : x < y , \; x \in A , \; y \in B\} \), then the difference between the sum of elements of domain and range of \( R \) is:
