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 (Clang 3.8.0) (judge verdict: Time Limit Exceeded)

#include <stdio.h>
#include <string.h>
#define SWAP(a,b) a=a+b,b=a-b,a=a-b
int main ()
{
	int a[200007];
	int i,j,ind=0,n;
	scanf ("%d",&n);
	for (i=1;i<=n;i++)
	{
		scanf ("%d",&a[i]);
	}
	for (i=0;i<=n-1;i++)
	{
		for (j=i+1;j<=n;j++)
		{
			if (a[i]>a[j])
			{
				SWAP(a[i],a[j]);
			}
		}
	}
	for (i=1;i<n;i++)
	{
		if (a[i]==a[i+1])
		{
			ind=1;
			break;
		}
	}
	if (ind==1)
	{
		printf ("NO\n");
	}
	else
	{
		printf ("YES\n");
	}
	return 0;
}