dates overlap dynamic

I need to calculate leaves (X, Y ) during a specified task by an employee.


Task Workdays
Start (Column D ) << >> End (Column E ) ------ Leaves days (column F )
1 10/10/2015 <<>> 11/15/2015 ---- X
2 11/27/2015 <<>> 12/27/2015 ---- Y
3. task3 (Start dt. <<>> End Dt. ) ------ Z
4. task4
5..... 2/5/2016 2/5/2015....


The leaves /Period :
Leaves
Column G << >> Column H
Start <<>> End
10/4/2015 <<>> 10/10/2015
11/10/2015 <<>>11/13/2015
12/2/2015 <<>> 12/8/2015
2/24/2015<<>> 1/1/2016
2/5/2016 <<>> 2/5/2015
and so on.......

The task list will be ever increasing, and so will be the leaves .

i need to find leaves taken during the the task 1 (X ) , similarly for task 2 (Y )
the leaves table will be say 200 rows to start with and gradually scalable, same with task list
also need to account workdays only (remove week ends )