Russian Doll Envelopes

You have a list of envelopes, who each have an integer width and height. An envelope can fit into another envelope if and only if the first envelope's width and height is smaller than the other envelope's width and height (you cannot rotate either envelopes).

Given a list of envelopes, find the maximum number of envelopes that you can fit inside one another like a Russian Doll.

Input

  • envelopes: a list of integer pairings representing the envelopes. For each pair, the first integer represents the width, and the second integer represents the height.

Output

The number representing the max envelope layers.

Examples

Example 1:

Input:

envelopes = [[5, 4], [6, 4], [6, 7], [2, 3]]

Output: 3

Explanation:

[2, 3] goes inside [5, 4], which goes inside [6, 7]

Constraints

  • 1 <= len(envelopes) <= 5000
  • 1 <= width[i], height[i] <= 10^4

Try it yourself

Solution

Title

Script

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.

Contrary to popular belief, Lorem Ipsum is not simply random text.

  >>> a = [1, 2, 3]
  >>> a[-1]
  3

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