foo.cc: In function 'int main()':
foo.cc:29:14: warning: 'w' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<q<<' '<<w;
  ~~~~~~~~~~~~^~~
foo.cc:29:11: warning: 'q' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<q<<' '<<w;
           ^~~

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