hello help me plz :

given :

in sheet 1 :

A B
3 a 1
4 b 2
5 c 3

in sheet 2 :

A B
1 c 4
2 d 5
3 a 3

in sheet 3 :

A B
2 e 6
3 f 7
4 g 8

NOW i would like to make in sheet 4 the following :
column a:a : the search string
and i would like to receive in column b:b their coresponding results..

thanks