Problem Statement

Given is a sequence of integers $A_1, A_2, ..., A_N$. If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

• $2 ≤ N ≤ 200000$
• $1 ≤ A_i ≤ 10^9$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.