The shortest way to get 24Generalization of flippo 24 game: every number can be used any number
of times. Number of input numbers is unrestricted. This version gives
a shortest way to get 24. Short is defined with respect to the depth of the
derivation for each of the numbers used in the final calculation.
Computations giving rise to integers outside the interval
-1000-1000 are not considered (otherwise the system load would become