The Stanley Cup playoffs are made up of four best-of-seven series. Each series is played in a 2-2-1-1-1 format, which means that the team with home-ice advantage hosts games 1, 2, 5, and 7, while the other team hosts games 3, 4, and 6, with games 5-7 being played if necessary. Teams then switch roles for games 1 and 2. The team that wins three out of four matches moves on to the next round, while the loser goes home. If the series remains tied three games each, then a tiebreaker game will be played using the same format as the previous three games. For example, if Game 5 ends in a tie, then the winner is determined by who has more goals after five minutes of overtime play. If the teams remain tied after this, then an instant replay review is used to determine a winner. There have been 12 ties and 13 penalty shots taken during playoff games over the history of the Stanley Cup. The first playoff series tie was in 1917 when the Montreal Canadiens and Boston Bruins both had 3 wins and 3 losses. Since then, there have been several other instances where two or more teams were tied at the end of the series. In all cases except one, they went on to play a deciding game seven. The only exception was in 1924 when the Ottawa Senators lost to the Chicago Black Hawks 4-3 in a game seven after winning three games in a row.