C# Puzzle No.9 (beginner)

Consider a delegate declaration which takes a function and returns another function:

delegate Func<int, int> FuncConversionDelegate( Func<int, int> Func );

Your goal is to write a lambda expression defining a converter which would negate values returned by original method:

FuncConversionDelegate Negation = 

    /* 

       replace this with a lambda expression 

       which takes function f and returns function g 

       so that g(x) = -f(x)

    */;

Specifically, you have to replace the commented expression above to a correct definition.

To test the converter, take the identity function:

static Func<int, int> Identity = x => x;

and apply Negation to it:

Negation( Identity )( 5 )

expecting the value of -5 to be returned.