foo.cc: In function 'void test()':
foo.cc:18:13: error: 'class std::vector<int>' has no member named 'sort'
   18 |         ans.sort();
      |             ^~~~
foo.cc:17:13: warning: unused variable 'num' [-Wunused-variable]
   17 |         int num=ans.size();
      |             ^~~

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