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

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("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 scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }

    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }

    } main {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }

    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int N = scanner.nextInt(); N scanner.nextInt() scanner.nextInt scanner Set<Integer> set = new HashSet<>(); set new HashSet<>() for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        } int i = 0 ; int i = 0 ; i 0 i < N i N i++ i++ i {
            set.add(scanner.nextInt());
        } {
            set.add(scanner.nextInt());
        } set.add(scanner.nextInt()) set.add set scanner.nextInt() scanner.nextInt scanner if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        } set.size() == N set.size() set.size set N {
            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 N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            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 N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }

    }
} Main

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

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        Set<Integer> set = new HashSet<>();
        for (int i = 0 ; i < N ; i++) {
            set.add(scanner.nextInt());
        }

        if (set.size() == N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }

    }
}
