### Phone Number

Time Limit: 1000 ms
Memory Limit: 65536 KiB

#### Problem Description

We know that if a phone number A is another phone number B’s prefix, B is not able to be called. For an example, A is 123 while B is 12345, after pressing 123, we call A, and not able to call B.

Given N phone numbers, your task is to find whether there exits two numbers A and B that A is B’s prefix.

Given N phone numbers, your task is to find whether there exits two numbers A and B that A is B’s prefix.

#### Input

The input consists of several test cases.

The first line of input in each test case contains one integer

The next line contains

The last case is followed by a line containing one zero.

The first line of input in each test case contains one integer

*N*(0<*N*<1001), represent the number of phone numbers.The next line contains

*N*integers, describing the phone numbers.The last case is followed by a line containing one zero.

#### Output

For each test case, if there exits a phone number that cannot be called, print “NO”, otherwise print “YES” instead.

#### Sample Input

2 012 012345 2 12 012345 0

#### Sample Output

NO YES

#### Hint

#### Source

2010年山东省第一届ACM大学生程序设计竞赛