foo.cc: In function 'int main()':
foo.cc:20:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |     scanf("%d%d%d",&L,&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:21:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   21 |     for (int i=1;i<=n;scanf("%d",&dis[i]),i++);//专业压行
      |                       ~~~~~^~~~~~~~~~~~~~

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