/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:44:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(register int i = 0; i < e[p].size(); i++) {
                             ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:68:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(register int j = 0; j < e[i].size(); j++) {
                                     ~~^~~~~~~~~~~~~