human
Give me a Python program to find the length longest chain which can be formed given the following:
I found an interesting problem on https://leetcode.com/problems/maximum-length-of-pair-chain/:
You are given n pairs of numbers. In every pair, the first number is always smaller than the second number.


Now, we define a pair (c, d) can follow another pair (a, b) if and only if b < c. Chain of pairs can be formed in this fashion. 


Given a set of pairs, find the length longest chain which can be formed. You needn't use up all the given pairs. You can select pairs in any order.


Example 1:

Input: [[1,2], [2,3], [3,4]]
Output: 2
Explanation: The longest chain is [1,2] -> [3,4]


Note:

The number of given pairs will be in the range [1, 1000].

I tried it in Python, but could not do it. Can you solve it?
assistant
#Here is Python program to find the length longest chain which can be formed.

class Solution:
     def findLongestChain(self, pairs):
         """
         :type pairs: List[List[int]]
         :rtype: int
         """
         queue = collections.deque(sorted(pairs, key=lambda pair: pair[1]))
         
         count = 0
         
         while len(queue) > 0:
           count += 1
           curr = queue.popleft()
           while len(queue) > 0 and queue[0][0] <= curr[1]:
             queue.popleft()
         
         return count