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



public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  }
 }
 import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections 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){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  }
 } Main public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  } main {
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc List<String> list = new ArrayList<>(); list new ArrayList<>() for(int i=0; i<N; i++) {
	   list.add(sc.next());
   } int i=0; int i=0; i 0 i<N i N i++ i++ i {
	   list.add(sc.next());
   } {
	   list.add(sc.next());
   } list.add(sc.next()) list.add list sc.next() sc.next sc Collections.sort(list) Collections.sort Collections list boolean flag = true; flag true for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   } int i=0; int i=0; i 0 i<list.size()-1 i list.size()-1 list.size() list.size list 1 i++ i++ i {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   } {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   } if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   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 {
	   flag = false;
	   break;
   } flag = false flag false break; if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   } flag == true flag true {
       System.out.print("YES");
   } System.out.print("YES") System.out.print System.out System System.out "YES" {
	   System.out.print("NO");
   } System.out.print("NO") System.out.print System.out System System.out "NO" String[] args args public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  }
 } public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   List<String> list = new ArrayList<>();
   for(int i=0; i<N; i++) {
	   list.add(sc.next());
   }
   Collections.sort(list);
   boolean flag = true;
   for(int i=0; i<list.size()-1; i++) {
   if(list.get(i).equals(list.get(i+1))) {
	   flag = false;
	   break;
   }
   }
   if(flag == true) {
       System.out.print("YES");
   }else {
	   System.out.print("NO");
   }
  }
 } Main
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;



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

