
import java.util.*;
import java.lang.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    }
} import java.util.*; util.* java import java.lang.*; lang.* java import java.util.stream.*; stream.* java.util public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    }
} Main public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    } main {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) Integer n = Integer.parseInt(scanner.next()); n Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner List<Long> listA = new ArrayList<Long>(); listA new ArrayList<Long>() Integer[] a = new Integer[n]; a new Integer[n] n for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        } {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        } listA.add(scanner.nextLong()) listA.add listA scanner.nextLong() scanner.nextLong scanner List<Long> listB = new ArrayList<Long>(new HashSet<>(listA)); listB new ArrayList<Long>(new HashSet<>(listA)) if(listA.size() == listB.size()) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        } listA.size() == listB.size() listA.size() listA.size listA listB.size() listB.size listB {
            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) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    }
} public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    }
} Main

import java.util.*;
import java.lang.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer n = Integer.parseInt(scanner.next());

        List<Long> listA = new ArrayList<Long>();

        Integer[] a = new Integer[n];
        for(int i = 0; i < a.length; i++) {
            listA.add(scanner.nextLong());
            //a[i] = Integer.parseInt(scanner.next());
        }

        List<Long> listB = new ArrayList<Long>(new HashSet<>(listA));

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

    }
}
