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();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);

        int count = 0;
        for(int i = 0; i < N-1; i++) {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        }
        if(count == 0) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} 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();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);

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

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

        int count = 0;
        for(int i = 0; i < N-1; i++) {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        }
        if(count == 0) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int[] arr = new int[N]; arr new int[N] N for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            arr[i] = sc.nextInt();
        } {
            arr[i] = sc.nextInt();
        } arr[i] = sc.nextInt() arr[i] arr i sc.nextInt() sc.nextInt sc Arrays.sort(arr) Arrays.sort Arrays arr int count = 0; count 0 for(int i = 0; i < N-1; i++) {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        } int i = 0; int i = 0; i 0 i < N-1 i N-1 N 1 i++ i++ i {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        } {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        } if(arr[i] == arr[i+1]) {
                count++;
            } arr[i] == arr[i+1] arr[i] arr i arr[i+1] arr i+1 i 1 {
                count++;
            } count++ count if(count == 0) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        } count == 0 count 0 {
            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);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);

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

        int count = 0;
        for(int i = 0; i < N-1; i++) {
            if(arr[i] == arr[i+1]) {
                count++;
            }
        }
        if(count == 0) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
} 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();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);

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