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>
int main()
{
	int n;
	scanf("%d",&n);
	int a[300000]={0};
	while(n--){
		int k;
		scanf("%d",&k);
		a[k]++;
	}
	int i;
	int flag=0;
	for(i=0;i<300000;i++){
		if(a[i]>1){
			flag=1;
			break;
		}
	}
	if(flag==1) printf("NO");
	else printf("YES");
	return 0;
}