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http://qiita.com/Nabetani/items/373105e7fafd12f5e9fd

```foldBase val (x:xs)
| x == 'F' = val ++ foldBase val xs
| x == 'R' = reverse(invert val) ++ foldBase val xs
| otherwise = x : foldBase val xs
foldBase _ [] = ""

invert ('F':xs) = 'R' : invert xs
invert ('R':xs) = 'F' : invert xs
invert ('m':xs) = 'V' : invert xs
invert ('V':xs) = 'm' : invert xs
invert [] = ""

foldL = foldBase "RVF"
foldJ = foldBase "FVR"
foldZ = foldBase "FmRVF"
foldU = foldBase "RVFVR"
foldS = foldBase "FVRmF"

filter' = filter(\x -> x == 'm' || x == 'V')

foldX x
| x == 'L' = foldL
| x == 'J' = foldJ
| x == 'Z' = foldZ
| x == 'U' = foldU
| x == 'S' = foldS

solve xs = filter' \$ foldl (\acc x -> foldX x acc) "F" xs

test input expected
| solve input == expected = putStrLn "OK"
| otherwise = putStrLn \$ "NG : " ++ input

main = do
test "JZ" "mVVmV"
test "J" "V"
test "L" "V"
test "Z" "mV"
test "U" "VV"
test "S" "Vm"
test "JL" "VVm"
test "JS" "VmVVm"
test "JU" "VVVmm"
test "LU" "mmVVV"
test "SL" "VVmmV"
test "SS" "VmVVmmVm"
test "SU" "VVVmmmVV"
test "SZ" "mVVmVmmV"
test "UL" "mVVVm"
test "UU" "mmVVVVmm"
test "UZ" "mVVmVVmV"
test "ZJ" "VmmVV"
test "ZS" "VmmVmVVm"
test "ZZ" "mVmmVVmV"
test "JJJ" "VVmVVmm"
test "JJZ" "mVVmVVmVmmV"
test "JSJ" "VVmmVVmVVmm"
test "JSS" "VmVVmmVmVVmVVmmVm"
test "JUS" "VmVVmVVmVVmmVmmVm"
test "JUU" "mmVVVVmmVVVmmmmVV"
test "JUZ" "mVVmVVmVVmVmmVmmV"
test "LJJ" "VmmVVVm"
test "LLS" "VmmVmVVmVVm"
test "LLU" "mmmVVVmmVVV"
test "LLZ" "mVmmVVmVVmV"
test "LSU" "mmVVVmmmVVVVmmmVV"
test "LSZ" "mVVmVmmVVmVVmVmmV"
test "LZL" "mmVVmVVmmVV"
test "LZS" "VmmVmVVmVVmmVmVVm"
test "LZU" "mmmVVVmmVVVmmmVVV"
test "SJL" "VVmVVmmmVVm"
test "SLU" "mmVVVVmmmVVmmmVVV"
test "SLZ" "mVVmVVmVmmVmmVVmV"
test "SSU" "VVVmmmVVVmmVVVmmmmVVVmmmVV"
test "SUJ" "mVVVmVVmmmVmmVVVm"
test "SUS" "VmVVmVVmVVmmVmmVmmVmVVmVVm"
test "SZZ" "mVmmVVmVVmVmmVVmVmmVmmVVmV"
test "UJJ" "VmmVVVmVVmm"
test "ULU" "mmmVVVmmVVVVmmmVV"
test "ULZ" "mVmmVVmVVmVVmVmmV"
test "UUU" "VVmmmmVVVmmVVVVmmVVVmmmmVV"
test "ZJU" "VVVmmmVVmmmVVVVmm"
test "ZLS" "VmVVmmVmmVmVVmVVm"
test "ZSJ" "VVmmVmmVVmmVVVmmV"
test "ZUJ" "mVVVmmVmmmVVmVVVm"
test "JJLJ" "mVVVmmVVmVVmmmV"
test "JLJJ" "VmmVVVmVVmmmVVm"
test "JLJL" "VmmVVVmVVmmmVVm"
test "LJJL" "VVmmVmmVVVmVVmm"
test "LLJJ" "VmmmVVmVVmmVVVm"
test "SZUS" "VmVVmVVmmVmmVmmVmVVmVVmVVmVVmmVmmVmmVmVVmVVmVVmmVmmVmmVmVVmVVmmVmmVmmVmVVmVVmVVm"
test "ULLS" "VmmVmmVmVVmVVmmVmVVmVVmVVmmVmmVmVVm"
test "JJJJZJ" "VmmVVVmmVVmVVmmVVmmmVVmVVmmVVVmmVVmmVmmVVmmmVVmVVmmVVVmmVVmVVmmVVmmmVVmmVmmVVVmmVVmmVmmVVmmmVVm"
test "JULLLJ" "mmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVVmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVmmmVmmVVmmmVVmVVmmmVmmVVVmmVVmVV"
test "LJJJUL" "mVVVmVVmmmVVmVVVmmVmmmVmmVVVmVVmmmVmmVVVmmVmmmVVmVVVmVVmmmVVmVVVmmVmmmVVmVVVmVVmmmVmmVVVmmVmmmV"
test "LJSJJL" "VVmVVmmVVVmmVmmmVVmVVmmmVVmmVmmVVVmVVmmmVVmmVmmVVVmVVmmVVVmmVmmmVVmVVmmVVVmmVmmVVVmVVmmmVVmmVmm"
test "LZLLLJ" "mmVmmVVmmmVVmVVmmmVmmVVVmmVVmVVVmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVVmmmVmmVVmmmVVmVVVmmVmmVVVmmVVmVV"
test "SJJJJL" "VVmVVmmVVVmmVmmVVVmVVmmmVVmmVmmVVVmVVmmVVVmmVmmmVVmVVmmmVVmmVmmmVVmVVmmVVVmmVmmVVVmVVmmmVVmmVmm"
test "ZLJLJL" "VmmVVVmmVmmmVVmVVmmVVVmVVmmmVVmmVmmVVVmmVmmmVVmmVmmVVVmVVmmmVVmVVmmVVVmmVmmmVVmVVmmVVVmVVmmmVVm"
```