import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    }
} import java.util.HashSet; HashSet java.util import java.util.Scanner; Scanner java.util import java.util.Set; Set java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Set<Integer> aSet = new HashSet<>(); aSet new HashSet<>() for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next())); int i = 0; int i = 0; i 0 i < n i n i++ i++ i aSet.add(Integer.parseInt(sc.next())); aSet.add(Integer.parseInt(sc.next())) aSet.add aSet Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc System.out.println(aSet.size() == n ? "YES" : "NO") System.out.println System.out System System.out aSet.size() == n ? "YES" : "NO" aSet.size() == n aSet.size() aSet.size aSet n "YES" "NO" String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    }
} Main
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> aSet = new HashSet<>();
        for(int i = 0; i < n; i++) aSet.add(Integer.parseInt(sc.next()));
        System.out.println(aSet.size() == n ? "YES" : "NO");
    }
}
