/in/foo.cc: In function 'void dfs(int, int, int, int)':
/in/foo.cc:68:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<edge[now].size();i++)
              ~^~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int kruskal()':
/in/foo.cc:177:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e.size();i++)
              ~^~~~~~~~~
/in/foo.cc: In function 'int sst(int)':
/in/foo.cc:198:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e.size();i++)
              ~^~~~~~~~~