List < List < Integer >> optimalUtilizationOnlyMani2(int deviceCapacity, List < List < Integer >> foregroundAppList, List < List < Integer >> backgroundAppList) {
	if (foregroundAppList == null || foregroundAppList.isEmpty() || backgroundAppList == null || backgroundAppList.isEmpty()) {
		return new ArrayList < >();
	}

	// map of memory and id of foreground app, id of background app
	List < List < Integer >> output = new ArrayList < >();

	Integer maximum_memory = Integer.MIN_VALUE;

	for (List < Integer > forgroundApp: foregroundAppList) {
		for (List < Integer > backgroundApp: backgroundAppList) {
			Integer combined_memory = forgroundApp.get(1) + backgroundApp.get(1);
			if (combined_memory <= deviceCapacity && combined_memory >= maximum_memory) {
				if (combined_memory > maximum_memory) {
					maximum_memory = combined_memory;
					output.clear();
				}

				output.add(Arrays.asList(forgroundApp.get(0), backgroundApp.get(0)));
			}
		}

	}

	return output;
}