foo.cc: In function 'int low_b(int, int, int)':
foo.cc:23:1: warning: control reaches end of non-void function [-Wreturn-type]
   23 | }
      | ^
foo.cc: In function 'int main()':
foo.cc:56:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   56 |  freopen("a.in","r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~

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