I try to overide — operator.
I want prefix and postfix — operator
but c# doesnot allowed it even that there is different signature’s function.
the code:

public static Rational operator --(Rational a)
{
    a.Mona -= a.Mechane;
    return a.reduce();
}
public static Rational operator --(Rational a, int _)
{
    _ = 0;
    Rational original = new Rational(a.Mona, a.Mechane);
    a.Mona -= a.Mechane;
    a.reduce();
    return original;
}

the error:

Overloadable binary operator expected

I tried to do two operators