import java .util.ArrayList;
import java.util.Collections;
import java .util.Scanner;
public class Main {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

}
} import java .util.ArrayList; ArrayList java .util import java.util.Collections; Collections java.util import java .util.Scanner; Scanner java .util public class Main {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

}
} Main public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

} main {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) ArrayList<Integer> inA = new ArrayList<>(); inA new ArrayList<>() int inputN = sc.nextInt(); inputN sc.nextInt() sc.nextInt sc Boolean boo = true; boo true for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	} int i = 0; int i = 0; i 0 i < inputN i inputN i++ i++ i {
		inA.add(sc.nextInt());
	} {
		inA.add(sc.nextInt());
	} inA.add(sc.nextInt()) inA.add inA sc.nextInt() sc.nextInt sc Collections.sort(inA, Collections.reverseOrder()) Collections.sort Collections inA Collections.reverseOrder() Collections.reverseOrder Collections for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	} int i = 0; int i = 0; i 0 i < inputN-1 i inputN-1 inputN 1 i++ i++ i {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	} {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	} int n = inA.get(i); n inA.get(i) inA.get inA i if(n == inA.get(i + 1)) {
				boo = false;
				break;

		} n == inA.get(i + 1) n inA.get(i + 1) inA.get inA i + 1 i 1 {
				boo = false;
				break;

		} boo = false boo false break; if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	} boo == true boo true {
		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);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

}
} public class Main {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

}
} Main
import java .util.ArrayList;
import java.util.Collections;
import java .util.Scanner;
public class Main {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);

	ArrayList<Integer> inA = new ArrayList<>();

	int inputN = sc.nextInt();
	Boolean boo = true;

	for(int i = 0; i < inputN; i++) {
		inA.add(sc.nextInt());
	}

	Collections.sort(inA, Collections.reverseOrder());

	for(int i = 0; i < inputN-1; i++) {
		int n = inA.get(i);
			if(n == inA.get(i + 1)) {
				boo = false;
				break;

		}

	}

	if(boo == true) {
		System.out.println("YES");
	}else {
		System.out.println("NO");
	}

}
}
