Question: For a contest, you are searching for the top-m popular students of the university. You are given friends list of n students where some students may appear several times. Count the unique number of friends for each student and identify the top popular student who has the most number of friends.

Input specification You will be given an integer in the beginning: the number of students (n). In each of the following n lines, you will be given several positive integers (friends of the current student) ending with a negative number where 0 ≤ n ≤ 8,000.

Output specification: Show the ID (order of appearance) of top student who has the most number of friends. If there are several students with the same number friends, first show the student with a smaller ID.

Explanation: Here is the list of students with their number of friends.
  1 -> 3
  2 -> 4
  3 -> 4
  4 -> 5
  5 -> 4
  6 -> 3
  7 -> 5