import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.BufferedWriter; BufferedWriter java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.OutputStreamWriter; OutputStreamWriter java.io import java.util.HashSet; HashSet java.util import java.util.Set; Set java.util public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    }
} Main public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    } main {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out)); bw new BufferedWriter(new OutputStreamWriter(System.out)) int n = Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br Set<Integer> set = new HashSet<>(); set new HashSet<>() String[] in = br.readLine().split(" "); in br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " br.close() br.close br for (String s : in) {
            set.add(Integer.parseInt(s));
        } String s in {
            set.add(Integer.parseInt(s));
        } {
            set.add(Integer.parseInt(s));
        } set.add(Integer.parseInt(s)) set.add set Integer.parseInt(s) Integer.parseInt Integer s bw.write(set.size() == n ? "YES" : "NO") bw.write bw set.size() == n ? "YES" : "NO" set.size() == n set.size() set.size set n "YES" "NO" bw.flush() bw.flush bw String[] args args public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    }
} public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    }
} Main
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        Set<Integer> set = new HashSet<>();
        String[] in = br.readLine().split(" ");

        br.close();

        for (String s : in) {
            set.add(Integer.parseInt(s));
        }

        bw.write(set.size() == n ? "YES" : "NO");

        bw.flush();

    }
}