Problem:
Score : 300 points

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.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in PyPy3 (2.4.0) (judge verdict: Wrong Answer)

#入力（後でいじる）
def pin(type=int):
    return map(type,input().split())
#どっかで最悪計算量の入力データを用意する関数を作ろう？
def worstdata():
    a=0
    return a
#solution:
def comp(p):#期待値
    return ((p+1)/2)



#input
n,=(pin())
S=sorted(list(pin()))
cond=1
for i in range(1,n):
    if S[i]-S[i-1]==0:
        cond=0
        break