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class Eqq a where
evenN :: a -> Bool
oddN :: a -> Bool
evenN x = False
oddN x = True
data N = Z | S N
instance Eqq N
where
evenN Z = True
evenN (S x) = oddN x
oddN Z = False
oddN (S x) = evenN x
choose x = if evenN x then "hello world (evenN)\n" else if oddN x then "hello world (oddN)\n" else "no!\n"
add n m =
case n of
Z -> m
S nn -> S (add nn m)
mul n m =
case n of
Z -> Z
S nn -> add m (mul nn m)
pow n m =
case m of
Z -> S Z
S mm -> mul n (pow n mm)
n1 = S Z
n2 = add n1 n1
n4 = add n2 n2
n6 = add n2 n4
n8 = add n2 n6
n10 = add n2 n8
n16 = add n6 n10
n18 = add n8 n10
n20 = add n4 n16
bign = pow n2 n16
bign1 = add bign n1
main = putStr (choose bign1)
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