Strictly Increasing Sequence

Problem Description

Determine whether a sequence of $n$ numbers is strictly increasing.

Input Format

The first line contains a positive integer $n(1 \lt n \le 1000)$.

The second line contains $n$ positive integers, all within the range of int.

Output Format

If the $n$ numbers are strictly increasing, print YES; otherwise print NO.

Sample Input

5
1 2 5 10 11

Sample Output

YES