There are $n$ couples sitting in $2n$ seats arranged in a row, who want to hold hands.

The people and seats are represented by an integer array row of length $2n$, where row[i] is the label of the person sitting in the $i$-th seat. The couples are ordered sequentially, meaning the first couple is $(0, 1)$, the second couple is $(2, 3)$, and so on, up to the final couple $(2n - 2, 2n - 1)$.

Return the minimum number of swaps needed so that every couple is seated side by side. A single swap consists of choosing any two individuals and having them exchange their seats.

Constraints:

• row.length $== 2n$

• $2 \leq n \leq 30$

• $0 \leq$ row[i] $< 2n$

• All the elements of row are unique.

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