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: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	String result = "YES";
	for (int i = 0; i < length - 2; i++) {
	    for (int j = i + 1; j < length - 1;) {
		if (strArray[i].equals(strArray[j])) {
		    result = "NO";
		    break;
		} else {
		    ++j;
		}
	    }
	}
	System.out.println(result);
    }
}