import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.HashSet; HashSet java.util import java.util.List; List java.util public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    }
} Main public static void main(String[] args) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    } main {
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    } BufferedReader input = new BufferedReader(new InputStreamReader(System.in)); input new BufferedReader(new InputStreamReader(System.in)) int n = Integer.parseInt(input.readLine()); n Integer.parseInt(input.readLine()) Integer.parseInt Integer input.readLine() input.readLine input String[] as = input.readLine().split(" "); as input.readLine().split(" ") input.readLine().split input.readLine() input.readLine input " " int a = as.length; a as.length as as.length List<String> list = new ArrayList<String>(Arrays.asList(as)); list new ArrayList<String>(Arrays.asList(as)) List<String> listdel = new ArrayList<String>(new HashSet<>(list)); listdel new ArrayList<String>(new HashSet<>(list)) int b = listdel.size(); b listdel.size() listdel.size listdel if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        } a == b a b {
            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) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    }
} public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(input.readLine());
        String[] as = input.readLine().split(" ");
        int a = as.length;
        List<String> list = new ArrayList<String>(Arrays.asList(as));
        List<String> listdel = new ArrayList<String>(new HashSet<>(list));
        int b = listdel.size();
        if(a == b ){
            System.out.println("YES");
        }else{
            System.out.println("NO");

        }
    }
}