Journey of a Knight

A rectangular chessboard has $n$ rows and $m$ columns, for a total of $n \times m$ cells. Each cell is identified by a pair of coordinates $(r, c)$, where $r$ is the row number ($1 \le r \le n$) and $c$ is the column number ($1 \le c \le m$). A knight starts on the bottom-left cell $(1, 1)$.

The knight moves according to the standard chess rules: in a single move it jumps one cell in one direction and two cells in the perpendicular direction (or two cells and then one cell). In other words, from cell $(r, c)$ the knight can move to any of the following eight cells that lie on the board: $(r \pm 1, c \pm 2)$ and $(r \pm 2, c \pm 1)$.

For example, if $n = 4$ and $m = 3$ and the knight is on cell $(2, 1)$, then in one move it can go to $(1, 3)$, $(3, 3)$, or $(4, 2)$.

You are given natural numbers $n$, $m$, $i$, $j$ ($1 \le n \le 100$, $1 \le m \le 100$, $1 \le i \le n$, $1 \le j \le m$). Determine the least possible number of moves the knight needs to reach cell $(i, j)$, starting from cell $(1, 1)$.

Pic. 1

Pic. 2

A single line containing four integers $n$, $m$, $i$, and $j$, separated by spaces.

Output the minimum number of moves required for the knight to reach cell $(i, j)$ from cell $(1, 1)$. If cell $(i, j)$ cannot be reached, output the single word NEVAR instead.