foo.cc: In function 'int main()':
foo.cc:15:12: warning: variable 'ex' set but not used [-Wunused-but-set-variable]
   15 |  int sx,sy,ex,ey;
      |            ^~
foo.cc:15:15: warning: variable 'ey' set but not used [-Wunused-but-set-variable]
   15 |  int sx,sy,ex,ey;
      |               ^~

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