Input:
30 29 5 5

#@#.DC.A.#A.##A@#AEECCD#.#..#

BB.BCAE.AEDDEEC.CAEBBEBAED@BE

.BDEABB#DDAD#.ACD#.A.#BCEEDDD

.BCEBAEA#EDEADA.#DE.D.ACDCE..

C.B#EE.CEBC##.BCBDBA#ADEBC.CA

.CABDD.DD.#E#CDBDC#CBBCEEBBBC

EE#B..ACEEAB.BE.EEB###CCABBAA

A###A#ABE#DC.DD#AD..EAAEDAAAA

DBCEEECAEBE.#D..EDECDAABAAD#A

DCC#BEDEBBAEBACDEDDECDDCBEBEC

.DB#E#E.DE.EC#.#EBA#DAEBE.E.#

#CAA#EEAE#.CACC.E.AE#BCA.CA.B

BB#AAD.A.#D..DB$EBAA.EC.##.E@

B.E#AD#D#DEEBEC.#DAEDABAA#BA#

BDCEAEAAD#..##A#.#DEBCCDCEAC#

#EBE.#AD..#ACAB.EEB#DEDCECEDC

ADA#BBBE.BABDBD#A#EBC.AABB#CA

@E.#DDDEAADE.D##E#C.AEA..AECD

CBABEDE#A#CAC.B..C.ABABCDEECD

#ACEEC.ABAD#DCCAE.#ADAACBAABA

#BA.EEC.#CD.BBBA#CEBDB.BEDB#C

ABDBD.A#B#E...BE#.#ACD.DDDA.C

C.CDCDADBBCBAACD#A#BC##E.BDAB

C#C#DBB#ADAE.ACEB#B.#C.AB#DCD

BB.CDD#DC.ABB..#EEBEBCA..#DED

.D#B..#C.A.E.DACB#.EC.CA#C.CE

.ADDEB#A##D#ECD#B.BAAEACDCCDC

.#C#AEBBA#EE.DA#.AAD.CDEC@.B#

B@CDBBBE#.CE#CCEEAAED.AEA#B#E

##AD#BAACDCDDAE@EC.CCDA#.#EBA

64 576 16 144 576 5184 144 1296 576 5184 144 1296 5184 46656 1296 11664 16 144 4 36 144 1296 36 324 144 1296 36 324 1296 11664 324 2916

Output:
0.831