import java.util.LinkedHashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		}
} import java.util.LinkedHashSet; LinkedHashSet java.util import java.util.Scanner; Scanner java.util import java.util.Set; Set java.util public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc String[] array = new String[n]; array new String[n] n for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        	array[i] = sc.next();
        } {
        	array[i] = sc.next();
        } array[i] = sc.next() array[i] array i sc.next() sc.next sc int bf = 0; bf 0 bf = array.length bf array.length array array.length int af = 0; af 0 Set<String> linkedHashSet = new LinkedHashSet<String>(); linkedHashSet new LinkedHashSet<String>() for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        } int i = 0; int i = 0; i 0 i < array.length i array.length array array.length i++ i++ i {
	        linkedHashSet.add(array[i]);
	        } {
	        linkedHashSet.add(array[i]);
	        } linkedHashSet.add(array[i]) linkedHashSet.add linkedHashSet array[i] array i Object[] strings_after = linkedHashSet.toArray(); strings_after linkedHashSet.toArray() linkedHashSet.toArray linkedHashSet af = strings_after.length af strings_after.length strings_after strings_after.length if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    } af == bf af bf {
	    	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){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		}
} Main
import java.util.LinkedHashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] array = new String[n];
        for (int i = 0; i < n; i++) {
        	array[i] = sc.next();
        }
		int bf = 0;
		bf = array.length;;
		int af = 0;
		Set<String> linkedHashSet = new LinkedHashSet<String>();
	    for (int i = 0; i < array.length; i++) {
	        linkedHashSet.add(array[i]);
	        }

	    Object[] strings_after = linkedHashSet.toArray();
	    af = strings_after.length;

	    if(af == bf){
	    	System.out.println("YES");
	    }else{
	    	System.out.println("NO");
	    }
		}
}