Given an array of integers. Write a program that determines if an array has a pair of adjacent elements with the same signs.
Input
First, the number N — the number of elements in the array (1 ≤ N ≤ 10000). Then N non-zero numbers are written separated by a space - the elements of the array. The array consists of integers.
Imprint
Output the word YES if there is a pair of neighboring elements with the same signs. Otherwise, output the word NO.
Examples
| # |
Input |
Output |
| 1 |
5
1 -3 4 -2 1
| NO |