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>

int YorN(int N, long s[]) {
	int flag = 0, i, j;
	for (i = 0; i < N; i++) {
		for (j = i + 1; j < N; j++) {
			if (s[i] == s[j]) {
				flag = 1;
			}
		}
	}
	return flag;
}

int main() {
	long str[200000];
	int N, i, j;
	scanf("%d", &N);
	for (i = 0; i < N; i++) {
		scanf("%d", &str[i]);
	}
	j = YorN(N, str);

	if (j == 0) {
		printf("YES");
	}
	else {
		printf("NO");
	}

	
	return 0;
}