SIRET, Romania (Reuters) -The European Union is preparing to grant Ukrainians who flee the war the right to stay and work in the 27-nation bloc for up to three years, senior European officials said on Monday, adding that EU border states would get help to cope with the arrivals. At least 400,000 Ukrainian refugees have entered the EU so far, EU Home Affairs Commissioner Ylva Johansson said. EU members Poland, Romania, Slovakia and Hungary have land borders with Ukraine. “We have to prepare for millions (to arrive in the EU),” Johansson told a news conference after a visit to a border crossing …