foo.cc: In function 'void init()':
foo.cc:17:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |     scanf("%d%d",&m,&n);
      |     ~~~~~^~~~~~~~~~~~~~
foo.cc:20:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |             scanf("%d",&w[i][j]);
      |             ~~~~~^~~~~~~~~~~~~~~

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