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: Runtime Error)

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

int main(void){

	int N;
	int count = 0;
	unsigned long int* A;
	unsigned long int* uniq;
	scanf("%d",&N);
	A = (unsigned long int*)calloc(sizeof(unsigned long int),N);
	uniq = (unsigned long int*)calloc(sizeof(unsigned long int),1000000000);
	for (int i = 0; i < N; ++i) {
		scanf("%lu",&A[i]);
		if (uniq[A[i]] == 0) uniq[A[i]] = A[i];
		else 	break;
		count++;
	}
	if (count == N) puts("Yes");
	else puts("No");

	free(A);
	free(uniq);

	return 0;
}