import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.Arrays; Arrays java.util public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    }
} Main public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    } main {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int length = Integer.parseInt(br.readLine()); length Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String strArray[] = br.readLine().split(" "); strArray br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int intArray[] = new int[length]; intArray new int[length] length for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	} int i = 0; int i = 0; i 0 i < length i length i++ i++ i {
	    intArray[i] = Integer.parseInt(strArray[i]);
	} {
	    intArray[i] = Integer.parseInt(strArray[i]);
	} intArray[i] = Integer.parseInt(strArray[i]) intArray[i] intArray i Integer.parseInt(strArray[i]) Integer.parseInt Integer strArray[i] strArray i Arrays.sort(intArray) Arrays.sort Arrays intArray String result = "YES"; result "YES" for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	} int j = 0; int j = 0; j 0 j < length - 1 j length - 1 length 1 {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	} {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	} if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    } intArray[j] == intArray[j + 1] intArray[j] intArray j intArray[j + 1] intArray j + 1 j 1 {
		result = "NO";
		break;
	    } result = "NO" result "NO" break; {
		j++;
	    } j++ j System.out.println(result) System.out.println System.out System System.out result String args[] args public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    }
} public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int length = Integer.parseInt(br.readLine());
	String strArray[] = br.readLine().split(" ");
	int intArray[] = new int[length];
	for (int i = 0; i < length; i++) {
	    intArray[i] = Integer.parseInt(strArray[i]);
	}

	Arrays.sort(intArray);
	String result = "YES";
	for (int j = 0; j < length - 1;) {
	    if (intArray[j] == intArray[j + 1]) {
		result = "NO";
		break;
	    } else {
		j++;
	    }
	}

	System.out.println(result);
    }
}