Upward Path

You are given a grid with $2$ rows and $N$ columns. The cell at the intersection of the $i$-th row and $j$-th column of the grid is denoted $(i, j)$. Each cell of the grid has a value: initially, the value at cell $(i, j)$ is denoted $A_{i, j}$. You can perform the following operation as many times as you like (possibly, zero times): - Choose a column and swap the values within it. Formally,