import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.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.ArrayList; ArrayList java.util import java.util.HashSet; HashSet java.util import java.util.List; List java.util public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.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 length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.size())
	    System.out.println("YES");
	else
	    System.out.println("NO");
    } main {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.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 length = Integer.parseInt(br.readLine()); length Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String strArray[] = br.readLine().split(" "); strArray br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " List<String> list = new ArrayList<String>(); list new ArrayList<String>() for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	} int i = 0; int i = 0; i 0 i < length i length i++ i++ i {
	    list.add(strArray[i]);
	} {
	    list.add(strArray[i]);
	} list.add(strArray[i]) list.add list strArray[i] strArray i List<String> newList = new ArrayList<String>(new HashSet<>(list)); newList new ArrayList<String>(new HashSet<>(list)) if (list.size() == newList.size())
	    System.out.println("YES");
	else
	    System.out.println("NO"); list.size() == newList.size() list.size() list.size list newList.size() newList.size newList System.out.println("YES") System.out.println System.out System System.out "YES" 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 length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.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 length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.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.ArrayList;
import java.util.HashSet;
import java.util.List;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");

	List<String> list = new ArrayList<String>();
	for (int i = 0; i < length; i++) {
	    list.add(strArray[i]);
	}

	List<String> newList = new ArrayList<String>(new HashSet<>(list));

	if (list.size() == newList.size())
	    System.out.println("YES");
	else
	    System.out.println("NO");
    }
}