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: Wrong Answer)

#include<stdio.h>
int main() {
	int i[1000000], j[1000000], k,m,n,x;
	scanf("%d", &k);
	for (m = 0;m < k;m++) {
		scanf("%d", &i[m]);
	}

	x = 0;

	for (n = 0;n < k;n++) {
		for (m = n+1;m < k;m++) {
			if (i[n] != i[m]) {
				x = 1;
			}
		}
	}
	if (x == 0) {
		printf("YES");
	}
	else {
		printf("NO");
	}
	return 0;
}