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>
#define k 200000
int main()
{
	int a[k],N,i,j;
	int flag = 0;
	scanf("%d",&N);
	for(i = 0; i < N; i++)
	scanf("%d",&a[i]);
	for(i = 0; i < N;i++)
		for(j = i+1; j < N; j++)
			if(a[i] == a[j])
			{
			flag = 1;
			break;
			}
	if(flag == 1)
	printf("NO\n");
	else
	printf("YES\n");
}