How is the lottery method for the 20 12 European Championship determined?

After the top 20 12 European Cup 16 was released, UEFA divided the promoted teams into four grades with reference to the scoring coefficients of teams in the last three international competitions. Among them, Poland and Ukraine, the two hosts, are not restricted by the scoring rules and rank first directly. Spain and the Netherlands, which ranked the top two in the scoring coefficient, occupied the other two seed teams in the first file. Germany, Italy, Britain and Russia ranked second; Portugal, Croatia, Greece and Sweden ranked third; The remaining Denmark, France, Czech Republic and Ireland ranked fourth.

First determine the group time of four first-level teams, then determine the group time of four second-level teams, and then determine the group time of three-level and four-level teams, so that the team of 16 is divided into four groups.