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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = sc.nextInt();
		int num[] = new int[200000];
		
		for(int i=0;i<200000;i++) {
			num[i]=0;
		}
		
		int judge = 1;
		for(int i=0;i<N;i++) {
			int input = sc.nextInt();
			num[i] = input;
			
			for(int j=0;j<i;j++) {
				if(num[j]==input) {
					judge = 0;
				}
			}
		}
		
		if(judge==1) {
			System.out.println("YES");
		}else{
			System.out.println("NO");
			}
	}
}