import java.util.*;
import java.util.Collections;
import java.util.ArrayList;

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

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
} import java.util.*; util.* java import java.util.Collections; Collections java.util import java.util.ArrayList; ArrayList java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    } main {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc String[] A = new String[N]; A new String[N] N ArrayList<String> list = new ArrayList<String>(); list new ArrayList<String>() for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        } int i=0; int i=0; i 0 i<N i N i++ i++ i {
            A[i] = sc.next();
            list.add(A[i]);
        } {
            A[i] = sc.next();
            list.add(A[i]);
        } A[i] = sc.next() A[i] A i sc.next() sc.next sc list.add(A[i]) list.add list A[i] A i Collections.sort(list) Collections.sort Collections list for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        } int i=0 ; int i=0 ; i 0 i<N-1 i N-1 N 1 i++ i++ i {
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        } {
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        } if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            } list.get(i).equals(list.get(i+1)) list.get(i).equals list.get(i) list.get list i list.get(i+1) list.get list i+1 i 1 {
                System.out.println("NO");
                break;
            } System.out.println("NO") System.out.println System.out System System.out "NO" break; if(i==N-2){
                System.out.println("YES");
            } i==N-2 i N-2 N 2 {
                System.out.println("YES");
            } System.out.println("YES") System.out.println System.out System System.out "YES" String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
} Main
import java.util.*;
import java.util.Collections;
import java.util.ArrayList;

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

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
}
