module EvenOdd;

data Nat = Zero | S(Nat);

def Bool even(Nat x) =
    case x {
    Zero => True;
    S(xP) => odd(xP);
};

def Bool odd(Nat x) =
    case x {
    Zero => False;
    S(xP) => even(xP);
};

def Bool start(Nat x) = even(x);

{

}