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: Time Limit Exceeded)

program abc65
 implicit none
 integer(8)::N,ia,ib,ic,j=1
 integer(8),allocatable::a(:)
 read(*,*)N
 allocate(a(N))
 read(*,*)(a(ia),ia=1,N)
 do ib=1,N-1
  do ic=ib+1,N
   if(a(ib)==a(ic))then
    j=0
    goto 1
   end if
  end do
 end do
 1 if(j==0)then
    print'(a)',"NO"
   else
    print'(a)',"YES"
   end if
 deallocate(a)
end program abc65