A city skyline can be represented as a 2-D array with 1s representing buildings. In the example below, the height of the tallest building is 4 (second-most right column).

[[0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0],
[0, 0, 1, 0, 1, 0],
[0, 1, 1, 1, 1, 0],
[1, 1, 1, 1, 1, 1]]

Create a function that takes a skyline (2-D array of 0's and 1's) and returns the height of the tallest skyscraper.

Examples

tallestSkyscraper([
  [0, 0, 0, 0],
  [0, 1, 0, 0],
  [0, 1, 1, 0],
  [1, 1, 1, 1]
]) ➞ 3

tallestSkyscraper([
  [0, 1, 0, 0],
  [0, 1, 0, 0],
  [0, 1, 1, 0],
  [1, 1, 1, 1]
]) ➞ 4

tallestSkyscraper([
  [0, 0, 0, 0],
  [0, 0, 0, 0],
  [1, 1, 1, 0],
  [1, 1, 1, 1]
]) ➞ 2

Notes

N/A