foo.cc: In function 'void init()':
foo.cc:38:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   38 | scanf("%d",&n);
      | ~~~~~^~~~~~~~~
foo.cc:40:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   40 | for(int j=1;j<=n+1;j++) scanf("%lf",&a[i][j]);
      |                         ~~~~~^~~~~~~~~~~~~~~~

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