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 Fortran (gfortran v4.8.4) (judge verdict: Time Limit Exceeded)

  Program Main

    Implicit None

    Integer, Allocatable :: A(:) 
    Integer(8)           :: i,j,N
    Logical              :: eq

    eq = .False.
    N  = 0
    Read(*,*) N
    Allocate (A(N)); A(:) = 0.0d0 
    Read(*,*)(A(i),i=1,N)

    Check:Do i = 1,N-1
             Do j = i+1,N
                If (A(i) == A(j)) then
                   eq = .True.
                   Exit Check
                Endif
             Enddo
          Enddo Check


    If (.not.eq) then
       Write(*,"(a)")"YES"
    Else
       Write(*,"(a)")"NO"
    Endif

    Deallocate(A)

  End Program