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