Update Different Groups of Data

[mathmath]

Hi All,
I have data like the following:
Stuff Sizes ID
pen s1 100001
pen s2 100002
pen s3 100003
pencil s1 100001
pencil s3 100004
pencil s5 100007
pencil s2 100006
ruler s7 100005
ruler s8 100008
..
..
where each size is coordinate with a unique ID number;
and there are 10 sizes (s1.....s10);

**i need to find out the HIGHEST ID number within each categories of stuff.
e.g pen (100003), pencil (10007),ruler(100008)

How should I do it?

Thank you all for your time.