pick out conserved introns between drosophila and Human

[HSV-1]

Hi, folks

I am interested in intron evolution. I have collected drosophila introns,... human introns, mouse introns....

I want to extract the conserved introns between drosophila and human.

My introns database are in fasta format. each intron record is like:
>chromo.... start base position number , end base position number....
GT............AG

What could I do to keep the introns that exist in drosophila and human?

Not easy for me.
Any suggestions are welcome!

Thanks.