foo.cc: In function 'int main()':
foo.cc:55:7: 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:57:27: 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);
   ~~~~~~~~~~~~~~           

[Hydro](https://hydro.ac)提供评测服务