Compare two columns in different sheet and retrive corrspo value

Hello,

How to compare two columns in one sheet with that of two columns in other sheet and retrive the corresponding Key value of the third column of the second sheet.
.
SHEET 1
A B C
1 W O
2 X P
3 Y Q
4 Z R


Sheet 2
A B C
1 Z R 10
2 X P 15
3 W O 20
4 Y Q 25

In the above example for Column C of Sheet 1 I want a formula where the corresponding calues of Column A & B in sheet 1 should match with that of sheet 2 and bring corresponding Value in Column C.

W & O of sheet one should bring value 20, the formula should search W and O then bring vlaue 20 under C1.

Regards,