import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    }
} import java.util.ArrayList; ArrayList java.util import java.util.HashSet; HashSet java.util import java.util.List; List java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    }
} Main public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    } main {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    } try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        } {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc StringBuilder result = new StringBuilder(); result new StringBuilder() List<Long> tmp = new ArrayList<>(); tmp new ArrayList<>() for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
                tmp.add(sc.nextLong());
            } {
                tmp.add(sc.nextLong());
            } tmp.add(sc.nextLong()) tmp.add tmp sc.nextLong() sc.nextLong sc result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO") result.append result new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO" new HashSet<Long>(tmp).size() == tmp.size() new HashSet<Long>(tmp).size() new HashSet<Long>(tmp).size new HashSet<Long>(tmp) tmp.size() tmp.size tmp "YES" "NO" System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    }
} public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    }
} Main
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in)) {
            int N = sc.nextInt();
            StringBuilder result = new StringBuilder();

            List<Long> tmp = new ArrayList<>();
            for (int i = 0; i < N; i++) {
                tmp.add(sc.nextLong());
            }

            result.append(new HashSet<Long>(tmp).size() == tmp.size() ? "YES" : "NO");

            System.out.println(result);
        }
    }
}