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 main(){
	int N;
	int A[200005];
	int flag=0;
	
	scanf("%d",&N);
	
	for(int i=0;i<N;i++){
		scanf("%d",&A[i]);
	}
	
	for(int i=0;i<N-1;i++){
		for(int j=i+1;j<N;j++){
			if(A[i]==A[j]){
			flag = 1;
//			printf("%d == %d",&A[i],A[j]);
			break;
			}
		}
	}
	
	if(flag == 1){
		printf("NO");
	}
	else printf("YES");

	return 0;
}