Create 1 long list from 3 columns?

My data is set up as

	A	B	C
1	A	B	C
2	D	E	F
3	G	H	I

How Can I make that data appear as

	A
1	A
2	B
3	C
4	D
5	E
6	F
7	G
8	H
9	I

Where is takes the row and keeps transposing it down 3 lines at a time?

Thanks!