Given a list of people with their birth and death years, implement a method to compute the year with the most number of people alive. You may assume that all people were born between 1900 and 2000 (inclusive). If a person was alive during any portion of that year, they should be included in that year's count. For example, Person (birth= 1908, death= 1909) is included in the counts for both 1908 and 1909.

If there are more than one years that have the most number of people alive, return the smallest one.

Example:

Input: 

birth = {1900, 1901, 1950}

death = {1948, 1951, 2000}

Output:  1901

Note:

• 0 < birth.length == death.length <= 10000
• birth[i] <= death[i]