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 Julia (0.5.0) (judge verdict: Accepted)

function main()
  
  N = parse(Int,readline())
  A = map(x -> parse(Int,x), split(readline()))
  
  sort!(A)
  check = true

  for i in 1:N-1

    if A[i] == A[i+1]
      println("NO")
      check = false
      break
    end
  end
  
  if check == true
    println("YES")
  end
  
end

main()