SQL & PL/SQL

Please help me to solve this issue..

If i have some data like the following..


ID           START DATE             END DATE

1             20080101              20080501
1             20080502              20080630
2             20080631              20080801
2             20080802              20080901
                                             ---------------> There is a break in date over here
2             20080930              20081029
2             20081030              20081130


I need to compare the End Date with the start date (These data will not be in order)
and find out if there is any break and should get the 

output date : *20080930*

I am trying to do this in SQL or PL/SQL.Please help me .

Thanks in advance.
phani