SQL & PL/SQL

I have a query:

select

  m.x1,

  round (to_date (l.y1, 'mm/dd/yyyy HH:MI:SS AM') - m.x2, 0) as numofdays

from

  table1 m,

  table2 l

where

  l.x3 = m.x3 and

  to_date (l.y1, 'mm/dd/yyyy HH:MI:SS AM') >= TO_DATE('01012013','MMDDYYYY') and

  ...;

and I got this result table:

several ID's have multiple values on the second column, I want to have only distinct IDs with smallest "numofdays" like this:

Any ideas?