[R] Extract letters from a column

[SH]

Dear list:

I would like to extract three letters from first and second elements
in one column and make a new column.

For example below,

> tempdf = read.table("clipboard", header=T, sep='\t')
> tempdf
              name var1 var2    abb
1      Tom Cruiser    1    6 TomCru
2       Bread Pett    2    5 BrePet
3 Arnold Schwiezer    3    7 ArnSch
> (p1 = substr(tempdf$name, 1, 3))
[1] "Tom" "Bre" "Arn"

I was able to extract three letters from first name, however, I don't
know how to extract three letters from last name (i.e., 'Cru', 'Pet',
and 'Sch').  Can anyone give me a suggestion?  Many thanks in advance.

Best,

Steve