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 (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program DorN
    implicit none
    integer(8) n, i
    integer :: f = 0
    integer(8),allocatable :: a(:)
    read *, n
    allocate(a(n))
    read *, a(1:n)
    do i = 1, n-1
        if(a(i) .eq. a(i+1))then
            f = f + 1
            exit
        end if
        if(f .ge. 1)exit
    end do
    if(f .ge. 1)then
        print *, 'NO'
    else
        print *, 'YES'
    end if
end program