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: Accepted)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;;
import java.util.stream.Stream;
public class Main {
  public static void main (String args[]) throws IOException{
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int inpLen = Integer.parseInt(br.readLine());
    String[] inpArr = br.readLine().split(" ");
    int[]  disInpArr= Stream.of(inpArr).distinct().mapToInt(Integer::parseInt).toArray();
    if(inpLen == disInpArr.length){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  }
}