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: Dr. John Ridge:  D'you know what I 've learned in the time I 've been with Doomwatch ? We 've got a generation in which to grow up . My generation ! Your generation ! During our lifetime , that 's if we get to three score year and _ ten _ . We 've got to get rid of warheads buzzing about up there round the clock and in submarines , also cruising round the clock . During our lifetime we 've got to control population , to control ionizing radiation . We 've got to cleanse the rivers and the seas , we 've got to unclog the air . And we 've got to have made a bloody good start by the time we 're dead or homo sapiens has had it : men perish from the Earth . We 've got to start washing underneath the arms and stop sweeping the muck underneath the carpet . We 've got to plant more trees than we cut down . We 've got to recycle the Earth 's resources , even our excrememnt and urine . We 've got to abolish the petrol engine or pay more for it . We 've got to pay more for everything . Our money or our life !

year