Epoka University is organizing Campus Tours for high schools of Tirana this Tuesday. Each high school though, can come within a certain time period [ai, bi] only.

Question: You want to find the minimum number of bus trips so that all high schools are satisfied and within their planned timeframe.

Input specification The first line of the input contains the number of schools (n). Each of the following n lines contains two integers a_i and b_i (separated by a space) defining available time frame of the i-th high school (the school will be happy if the bus takes students within this time frame) where n is between 1 and 40,000 and 0 ≤ a_i ≤ b_i ≤ 23.

Output specification First print the minimum number m of time points on the first line and the integer values of m time points (separated by spaces) on the second line.

Explanation: (for Sample 1:) There are three schools coming. And all schools are available at three o'clock. One bus is sufficient to take students from all three schools.