No New Friends

You are given n people represented as an integer from 0 to n - 1, and a list of friends tuples, where person friends[i][0] and person friends[i][1] are friends.

Return whether everyone has at least one friend.

Constraints

• m ≤ 100,000 where m is the length of friends

https://binarysearch.com/problems/No-New-Friends

Examples

Example 1

Input

• n = 3
• friends =

[[0,1]]

Output

• answer = False

Explanation

Person 2 is not friends with anyone.

Example 2

Input

• n = 3
• friends =

[[0,1],
 [1,2]]

Output

• answer = True

Explanation

• Person 0 is friends with 1
• Person 1 is friends with 0 and 2
• Person 2 is friends with 1.

Solution