foo.cc: In function 'int main()':
foo.cc:49:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&n,&m,&l);
  ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:51:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d",&u,&v,&w),
   ~~~~~~~~~~~~~~~~~~~~~~~~^~
   addedge(u,v,w);
   ~~~~~~~~~~~~~~           

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