import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Main{
  public static void main(String[] args)throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      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.HashSet; HashSet java.util import java.util.Set; Set java.util public class Main{
  public static void main(String[] args)throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    }
  }
} Main public static void main(String[] args)throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    }
  } main {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    }
  } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int numAll = Integer.parseInt(br.readLine()); numAll Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String[] numsStr = br.readLine().split(" "); numsStr br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " Set<String> numSet = new HashSet<>(); numSet new HashSet<>() for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    } int i=0; int i=0; i 0 i<numAll i numAll i++ i++ i {
      numSet.add(numsStr[i]);
    } {
      numSet.add(numsStr[i]);
    } numSet.add(numsStr[i]) numSet.add numSet numsStr[i] numsStr i if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    } numAll == numSet.size() numAll numSet.size() numSet.size numSet {
      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 br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    }
  }
} public class Main{
  public static void main(String[] args)throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      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.HashSet;
import java.util.Set;

public class Main{
  public static void main(String[] args)throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    int numAll = Integer.parseInt(br.readLine());
    
    String[] numsStr = br.readLine().split(" ");
  
    Set<String> numSet = new HashSet<>();
    
    for(int i=0; i<numAll; i++){
      numSet.add(numsStr[i]);
    }
    
    if(numAll == numSet.size()){
      System.out.println("YES");
    } else {
      System.out.println("NO");
    }
  }
}