/in/foo.cc: In function 'void dfs_ori(int)':
/in/foo.cc:29:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < G_ori[x].size(); i++)
                   ~~^~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs_trans(int)':
/in/foo.cc:44:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < G_trans[x].size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int dfs_sum(int)':
/in/foo.cc:58:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < G_shrink[x].size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:122:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0; j < G_ori[i].size(); j++)
                     ~~^~~~~~~~~~~~~~~~~