Problem 54: Is It Strictly Increasing?

An integer N is given on the first line, and N integers are given on the second line, separated by spaces. If the sequence is always strictly increasing (left < right for every pair of adjacent elements), output Yes; otherwise, output No. When N is 1, output Yes.

Constraints

1 ≤ N ≤ 100, 0 ≤ each element ≤ 1000

Input example 1

4
1 3 5 9

Output example 1

Yes

Input example 2

3
2 2 3

Output example 2

No