foo.cc: In function 'int main()':
foo.cc:62:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   62 |   scanf("%lf%lf",&zsd[i][0],&zsd[i][1]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:65:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   65 |   scanf("%lf%lf",&ren[i][0],&ren[i][1]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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