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: Time Limit Exceeded)

#include <stdio.h>
#include <stdlib.h>

int main() {
	long N;
	scanf("%d",&N);
	long *p = (long*)malloc(sizeof(long)*N);
	
	for (long i = 0;i < N;i++) {
		scanf("%ld",p+i);
	}
	
	for (long j = 0;j < N-1;j++) {
		for (long k = j+1;k < N;k++) {
			if (p[j] == p[k]) {
				printf("NO");
				return 0;
			}
		}
	}
	printf("YES");
	return 0;
}