import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util import java.util.Scanner; Scanner java.util import java.util.stream.Collectors; Collectors java.util.stream public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} Main public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    } main {
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int count = scanner.nextInt(); count scanner.nextInt() scanner.nextInt scanner scanner.nextLine() scanner.nextLine scanner List<Integer> list = new ArrayList<>(); list new ArrayList<>() for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        } int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
            list.add(scanner.nextInt());
        } {
            list.add(scanner.nextInt());
        } list.add(scanner.nextInt()) list.add list scanner.nextInt() scanner.nextInt scanner if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        } list.stream().distinct().collect(Collectors.toList()).size() == list.size() list.stream().distinct().collect(Collectors.toList()).size() list.stream().distinct().collect(Collectors.toList()).size list.stream().distinct().collect(Collectors.toList()) list.stream().distinct().collect list.stream().distinct() list.stream().distinct list.stream() list.stream list Collectors.toList() Collectors.toList Collectors list.size() list.size list {
            System.out.println("YES");
        } System.out.println("YES") System.out.println System.out System System.out "YES" {
            System.out.println("NO");
        } System.out.println("NO") System.out.println System.out System System.out "NO" String[] args args public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} Main
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int count = scanner.nextInt();
        scanner.nextLine();
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < count; i++){
            list.add(scanner.nextInt());
        }
        if(list.stream().distinct().collect(Collectors.toList()).size() == list.size()){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}
