foo.cc: In function 'int main()':
foo.cc:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   19 |  scanf("%d%d%d",&n,&m,&k);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:20:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |  for(int i=1;i<=m;i++) scanf("%d%d%d",&edge[i].x,&edge[i].y,&edge[i].w);
      |                        ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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