Working out the distribution

Working out the distribution

10 5 4 2
A 2
10 8 6
Q J 9 3
N
W   E
 
S
A J 8 7
6
A 7 5
A K 10 5 4

Dealer:

East

W N E S
1 2
2 3 3 4
End

Contract:

4 by South

Lead:

3

(Partner's 3 shows exactly 4 cards, with unspecified point count.)

Pause to think. What do opponents have?