After using all of their main time, a player must make a certain number of moves within a certain period of time — for example, twenty moves within five minutes. In Go, players stop the clock, and the player in overtime counts out the required number of stones and sets the remaining stones out of reach so as not to become confused, whilst the opponent sets the clock to the overtime period. If all the moves are made in time, then another period of overtime starts — another set of stones and the timer again reset to the overtime period. If all the moves are not made in time, the player has "lost on time". This is written as <main time> + <number of moves to be completed in each time period> in <time period>. In Progressive Canadian Overtime the required rate of play alters in additional overtime periods — EG 1hour + 10 in 5, 20 in 5, 30 in 5, 40 in 5 etc.