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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<algorithm>
using namespace std;
int A[210000];

int main()
{
	int N;
	scanf("%d", &N);
	for (int i = 0; i < N; ++i)
	{
		scanf("%d", A + i);
	}
	std::sort(A, A + N);
	for (int i = 0; i < N - 1; ++i)
	{
		if (A[i] == A[i + 1])
		{
			printf("NO\n");
			return 0;
		}
	}
	printf("YES\n");
}