/in/foo.cc: In function 'int main()':
/in/foo.cc:15:26: warning: 't' may be used uninitialized in this function [-Wmaybe-uninitialized]
  eg[++cnt].d=v, eg[cnt].w= w, eg[cnt].next=head[u], head[u]=cnt;
                 ~~~~~~~~~^~~
/in/foo.cc:34:12: note: 't' was declared here
  int u,v,k,t;
            ^