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++ (GCC 5.4.1) (judge verdict: Runtime Error)

#include<cstdio>
using namespace std;
int vis[10000010];
int n,a;
int main()
{
	scanf("%d",&n);
	while(n--)
	{
		scanf("%d",&a);
		if(!vis[a]) vis[a]=1;
		else 
		{
			printf("NO\n");
			return 0;
		}
	}
	printf("YES\n");
	return 0;
}