[R] how to merge two data.frames – only complete observations

[Martin Batholdy]

Hi,


I have two data-frames like:

A:
USA	3.2
Canada	4.7
Austria	1.5
Iran		0.3
China	3.8
Japan	3.0

B:
Austria	17
Iran		22
Angola	29
Japan	32
England	11


Now I want to merge this two data.frames to one - 
but I only want entries for the countries I have complete observations for;

so the final data.frame should look like this:

C:
Austria	1.5	17
Iran		0.3	22
Japan	3.0	32	


How can I do this?