import java.util.*;

public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	}
} import java.util.*; util.* java public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	}
} Main public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int a[] = new int[n]; a new int[n] n for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt(); int i = 0; int i = 0; i 0 i < n i n ++i ++i i a[i] = sc.nextInt(); a[i] = sc.nextInt() a[i] a i sc.nextInt() sc.nextInt sc sc.close() sc.close sc String ans[] = { "YES", "NO" }; ans { "YES", "NO" } "YES" "NO" int an = 0; an 0 Arrays.sort(a) Arrays.sort Arrays a int t = a[0]; t a[0] a 0 for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		} int i = 1; int i = 1; i 1 i < n i n ++i ++i i {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		} {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		} if (t == a[i]) {
				an = 1;
				break;
			} t == a[i] t a[i] a i {
				an = 1;
				break;
			} an = 1 an 1 break; t = a[i] t a[i] a i System.out.println(ans[an]) System.out.println System.out System System.out ans[an] ans an String args[] args public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	}
} public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	}
} Main
import java.util.*;

public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a[] = new int[n];
		for (int i = 0; i < n; ++i)
			a[i] = sc.nextInt();
		sc.close();
		String ans[] = { "YES", "NO" };
		int an = 0;
		Arrays.sort(a);
		int t = a[0];
		for (int i = 1; i < n; ++i) {
			if (t == a[i]) {
				an = 1;
				break;
			}
			t = a[i];
		}
		System.out.println(ans[an]);
	}
}
