Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: Captain Jack Harkness:  But all the legends of Gallifrey made it sound so perfect .
The Doctor: Well , perfect to look at , maybe . And it was , it was beautiful . They used to call it the Shining World of the Seven Systems . And on the continent of Wild Endeavour , in the mountains of Solace and Solitude , there stood the Citadel of the Time Lords . The oldest and most mighty race in the universe . Looking down on the galaxies below , sworn never to interfere , only to watch . Children of Gallifrey were taken from their families at the age of _ eight _ to enter the Academy . Some say that 's where it all began , when he was a child . That 's when the Master saw eternity . As a novice , he was taken for initiation . He stood in front of the Untempered Schism . It 's a gap in the fabric of reality through which could be seen the whole of the vortex . We stand there , eight years old , staring at the raw power of time and space , just a child . Some would be inspired . Some would run away . And some would go mad .
Martha Jones: What about you ?
The Doctor: Oh , the ones that ran away , I never stopped .

age