import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Arrays;
import java.util.Collections;
class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    Integer A[] = new Integer[N];
    for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    }
    Arrays.sort(A, Collections.reverseOrder());
    for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    }
    System.out.println("YES");    
  }
} import java.util.Scanner; Scanner java.util import java.util.List; List java.util import java.util.ArrayList; ArrayList java.util import java.util.Comparator; Comparator java.util import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    Integer A[] = new Integer[N];
    for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    }
    Arrays.sort(A, Collections.reverseOrder());
    for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    }
    System.out.println("YES");    
  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    Integer A[] = new Integer[N];
    for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    }
    Arrays.sort(A, Collections.reverseOrder());
    for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    }
    System.out.println("YES");    
  } main {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    Integer A[] = new Integer[N];
    for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    }
    Arrays.sort(A, Collections.reverseOrder());
    for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    }
    System.out.println("YES");    
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int N = scan.nextInt(); N scan.nextInt() scan.nextInt scan Integer A[] = new Integer[N]; A new Integer[N] N for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    } int i = 0 ; int i = 0 ; i 0 i < N i N i++ i++ i {
      A[i] = scan.nextInt();
    } {
      A[i] = scan.nextInt();
    } A[i] = scan.nextInt() A[i] A i scan.nextInt() scan.nextInt scan Arrays.sort(A, Collections.reverseOrder()) Arrays.sort Arrays A Collections.reverseOrder() Collections.reverseOrder Collections for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    } int i = 0 ; int i = 0 ; i 0 i < N - 1 i N - 1 N 1 i++ i++ i {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    } {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    } if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      } A[i].equals(A[i + 1]) A[i].equals A[i] A i A[i + 1] A i + 1 i 1 {
        System.out.println("NO");  
        return;
      } System.out.println("NO") System.out.println System.out System System.out "NO" return; System.out.println("YES") System.out.println System.out System System.out "YES" String[] args args
import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Arrays;
import java.util.Collections;
class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    Integer A[] = new Integer[N];
    for (int i = 0 ; i < N ; i++) {
      A[i] = scan.nextInt();
    }
    Arrays.sort(A, Collections.reverseOrder());
    for (int i = 0 ; i < N - 1 ; i++) {
      if(A[i].equals(A[i + 1])){
        System.out.println("NO");  
        return;
      }
    }
    System.out.println("YES");    
  }
}