std::sort(newcmds.begin(), newcmds.end());
std::set_difference(cmds.begin(), cmds.end(), newcmds.begin(), newcmds.end(), removed.begin());
std::sort(newcmds.begin(), newcmds.end());
std::set_difference(cmds.begin(), cmds.end(), newcmds.begin(), newcmds.end(), removed.begin());