/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:9:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i=0;i<f[p].size();i++) 
                 ~^~~~~~~~~~~~
/in/foo.cc: In function 'int bfs()':
/in/foo.cc:20:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0 ; i < e[p.first].size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j = 0 ;j <e[i].size() ;j++)
                  ~~^~~~~~~~~~~~