Sets, Relations and Functions: JEE Main 2025 Mathematics question

Let $\mathbf{R} = \{(1, 2), (2, 3), (3, 3)\}$ be a relation defined on the set $\{1, 2, 3, 4\}$. Then the minimum number of elements, needed to be added in $\mathbf{R}$ so that $\mathbf{R}$ becomes an equivalence relation, is