
import java.util.*;

public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
} import java.util.*; util.* java public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
} Main public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    } main {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    } boolean ans=true; ans true Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int size=sc.nextInt(); size sc.nextInt() sc.nextInt sc int elements[]=new int[ size]; elements new int[ size] size for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        } int i=0; int i=0; i 0 i<size i size i++ i++ i {
        	elements[i]=sc.nextInt();
        	   	
        } {
        	elements[i]=sc.nextInt();
        	   	
        } elements[i]=sc.nextInt() elements[i] elements i sc.nextInt() sc.nextInt sc Arrays.sort(elements) Arrays.sort Arrays elements for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        } int j=size-1; int j=size-1; j size-1 size 1 j>0 j 0 j-- j-- j {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        } {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        } if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        } elements[j]==elements[j-1] elements[j] elements j elements[j-1] elements j-1 j 1 {
        	ans=false;
        	break;
        } ans=false ans false break; if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        } ans 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" sc.close() sc.close sc String args[] args public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
} public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
} Main

import java.util.*;

public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
}