Social problems are classified into a total of 10 categories as follows.
1. Low birth rate and super-aging
2. Inequality problem
3. Instability of future generations' lives
4. Job insecurity
5. Environmental impacts between countries
6. Cybercrime
7. Energy and resource depletion
8. North Korea, Security, and Unification
9. Climate change and natural disasters
10. Transition between low growth and growth strategy
11. Unclassifiable
Write only the corresponding number to which of the 10 types of social problems the text separated by triple quotation marks below belongs to.

We present an efficient algorithm for  chart-based phrase structure parsing  of  natural language  that is tailored to the problem of extracting specific information from  unrestricted texts  where many of the  words  are unknown and much of the  text  is irrelevant to the task. The  parser  gains algorithmic efficiency through a  reduction  of its  search space  . As each new  edge  is added to the  chart  , the algorithm checks only the topmost of the  edges  adjacent to it, rather than all such  edges  as in conventional treatments. The resulting  spanning edges  are insured to be the correct ones by carefully controlling the order in which  edges  are introduced so that every final  constituent  covers the longest possible  span  . This is facilitated through the use of  phrase boundary heuristics  based on the placement of  function words  , and by  heuristic rules  that permit certain kinds of  phrases  to be deduced despite the presence of  unknown words  . A further  reduction in the search space  is achieved by using  semantic  rather than  syntactic categories  on the  terminal and non-terminal edges  , thereby reducing the amount of  ambiguity  and thus the number of  edges  , since only  edges  with a valid  semantic  interpretation are ever introduced.  Provide your reponse without using the word unclassifiable.
user