Dropped Sensor Metric

You are given two lists of integers a and b representing sensor metrics. Each list contains unique integers and a ≠ b. One of the lists contains accurate sensor metrics but the other one is faulty. In the faulty list one number that wasn’t the last number was dropped and a fake value was appended to the end of the list. Return the number that was dropped.

Constraints

• 2 ≤ n ≤ 100,000 where n is the length of a and b

https://binarysearch.com/problems/Dropped-Sensor-Metric

Examples

Example 1

Input

• a = [1, 2, 3]
• b = [2, 3, 5]

Output

• answer = 1

Explanation

The accurate metrics come from a = [1, 2, 3].

Example 2

Input

• a = [5, 4, 2, 1, 6]
• b = [5, 4, 3, 2, 1]

Output

• answer = 3

Explanation

The accurate metrics come from b = [5, 4, 3, 2, 1].

Solution