Given a 2-D grid of characters board and a string word, return true if the word is present in the grid, otherwise return false.

For the word to be present it must be possible to form it with a path in the board with horizontally or vertically neighboring cells. The same cell may not be used more than once in a word.

Example 1:

Input: 
board = [
  ["A","B","C","D"],
  ["S","A","A","T"],
  ["A","C","A","E"]
],
word = "CAT"

Output: true

Example 2:

Input: 
board = [
  ["A","B","C","D"],
  ["S","A","A","T"],
  ["A","C","A","E"]
],
word = "BAT"

Output: false

Constraints:

• 1 <= board.length, board[i].length <= 5
• 1 <= word.length <= 10
• board and word consists of only lowercase and uppercase English letters.