import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	}
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc long[] arr = new long[200000]; arr new long[200000] 200000 for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		} int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
			arr[i] = sc.nextLong();
		} {
			arr[i] = sc.nextLong();
		} arr[i] = sc.nextLong() arr[i] arr i sc.nextLong() sc.nextLong sc Arrays.sort(arr) Arrays.sort Arrays arr for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		} int i = 1; int i = 1; i 1 i < 200000 i 200000 i++ i++ i {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		} {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		} if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			} arr[i] > 0 arr[i] arr i 0 {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			} if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				} arr[i] == arr[i - 1] arr[i] arr i arr[i - 1] arr i - 1 i 1 {
					System.out.println("NO");
					break;
				} System.out.println("NO") System.out.println System.out System System.out "NO" break; if (i == 200000 - 1) {
				System.out.println("YES");
			} i == 200000 - 1 i 200000 - 1 200000 1 {
				System.out.println("YES");
			} System.out.println("YES") System.out.println System.out System System.out "YES" String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	}
} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		long[] arr = new long[200000];

		for (int i = 0; i < N; i++) {
			arr[i] = sc.nextLong();
		}

		Arrays.sort(arr);

		for (int i = 1; i < 200000; i++) {
			if (arr[i] > 0) {
				if (arr[i] == arr[i - 1]) {
					System.out.println("NO");
					break;
				}
			}
			if (i == 200000 - 1) {
				System.out.println("YES");
			}
		}
	}
}