format that was introduced in 1997. It has a knock-out format with 32 players, contested over 17 days ending on the first Monday in May, which is May Day bank holiday in the United Kingdom. Of the 32 players, 16 reach the final stages automatically while the other 16 need to earn a place through a qualifying competition. The reigning world champion receives a direct entry and is the number one seed (the World Champion is usually seeded at least 2nd for all ranking tournaments, and The Masters, for the following season). The remaining direct entries are based on the latest world rankings, players being seeded based on these world rankings. Since the defending champion is normally ranked in the top 16, the top 16 ranked players generally receive a direct entry. Before 1982, there were a number of different formats used for the championship. In 1980 and 1981, 24 players competed in the final stages at the Crucible; the top eight seeds had a bye in the first round while seeds 9 to 16 played in the first round against eight qualifiers. From 1977 to 1979, the first three years at the Crucible, only 16 players reached the final stages, eight seeds playing eight qualifiers in the first round. The current length format of matches per round is as follows. The first round is played over best of 19 frames, played over two sessions. The second round and quarter-finals are the best of 25 frames played over three sessions; while the semi-finals and final are played over four sessions, the semi-finals being best of 33 frames and the final being best of 35 frames. For the first 12 days of the tournament, until the end of the quarter-final stage, two matches are played concurrently. For the last five days (the semi-finals and final) only one table is used. From 1980–1996, the semi-finals were played over best of 31 frames, before this was changed from 1997 onwards to best of 33 frames. The Championship has nearly always ended on the first Monday in May since the Championship first became a 17-day event in 1982, but there have been five exceptions. In 1982, the Championship ended on Sunday 16 May; while in 1985, 1990 and 1995, the Championship ended on the last Sunday in April. In all four of those years, the tournament started on a Friday rather than a Saturday.