public static readonly int MAX_DEPTH = 500000; // 500K searches
public static int unaquirableResources(BuildingGS currentGS, BuildingGS targetGS)
{
// Are there any resources that are impossible to get at this moment (ignoring workers)
HashSet <ResourceType> unaquirableResources = targetGS.getCPTResourceTypes();
unaquirableResources.ExceptWith(currentGS.slotsForIncome());
return(unaquirableResources.Count);
}