If it is possible to find a sleep schedule that allows you to participate in all planned activities in their entirety, then output such a schedule in the format described below. Otherwise, output impossible.

A sleep schedule is specified by a line containing the number p (1≤p≤10^6) of sleep periods, followed by p lines. The ith of these lines contains two integers s_i and t_i — the beginning and end time of the ith sleep period, counted in minutes from the beginning of the Finals. Note that you should not output any sleep period after the last activity.

The sleep periods must satisfy 0=s_1<t_1<s_2<t_2<\dots <t_p≤b_n as well as the condition described in the statement that does not allow you to fall asleep for some time after a sleep period. You may fall asleep immediately after an activity (so it may be that s_i=e_j) and you may wake up just before an activity (so it may be that t_i=b_j).

If there are multiple valid sleep schedules, any one will be accepted. It can be shown that if there is a valid sleep schedule, then there is also one with at most 10^6 sleep periods.

#8291 upload - done - how_to_reg -

Jet Lag timer 2s memory 1024MB

#8291

Jet Lag 2s 1024MB