Equal Values

Write a program that reads one or more nonnegative integers from the standard input line by line. If the first number of the line is 0, the program should end its operation. If the first number of the line is positive, it indicates the number of additional numbers in the line.

For each input line, the program should write the string „YES” to the standard output if the second number in the line is the same as the last one, otherwise the string „NO” should be printed.

Sample Input

1. 4 2 5 2 1
2. 5 11 5 133 62 11
3. 1 1
4. 4 1 0 1 2
5. 3 1 0 1
6. 0

Output for Sample Input

1. NO
2. YES
3. YES
4. NO
5. YES