foo.cc: In function 'int main()':
foo.cc:35:17: warning: unused variable 'u' [-Wunused-variable]
     for(int i=1,u,v;i<=m;++i)
                 ^
foo.cc:35:19: warning: unused variable 'v' [-Wunused-variable]
     for(int i=1,u,v;i<=m;++i)
                   ^
foo.cc:33:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&n,&m);
     ~~~~~^~~~~~~~~~~~~~
foo.cc:34:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;++i)scanf("%d%d",&x[i],&y[i]);
                          ~~~~~^~~~~~~~~~~~~~~~~~~~
foo.cc:37:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&e[i].u,&e[i].v);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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