Problem: PolandBall is a young, clever Ball. He is interested in prime numbers. He has stated a following hypothesis: "There exists such a positive integer n that for each positive integer m number n·m + 1 is a prime number".

Unfortunately, PolandBall is not experienced yet and doesn't know that his hypothesis is incorrect. Could you prove it wrong? Write a program that finds a counterexample for any n.

Input

The only number in the input is n (1 ≤ n ≤ 1000) — number from the PolandBall's hypothesis. 

Output

Output such m that n·m + 1 is not a prime number. Your answer will be considered correct if you output any suitable m such that 1 ≤ m ≤ 103. It is guaranteed the the answer exists.

Examples

Input

3


Output

1

Input

4


Output

2

Note

A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

For the first sample testcase, 3·1 + 1 = 4. We can output 1.

In the second sample testcase, 4·1 + 1 = 5. We cannot output 1 because 5 is prime. However, m = 2 is okay since 4·2 + 1 = 9, which is not a prime number.

Solution (in JAVA):

Solution:
/*
Author - Ayub Subhaniya
Institute - DAI-ICT
*/
import java.io.*;
import java.util.*;
import java.math.*;
public class Venture8C {
	static InputReader in=new InputReader(System.in);
	static OutputWriter out=new OutputWriter(System.out);
	static long mod;
	public static void main(String[] args) {
//		int t=in.nextInt();
//		while (t-->0)
//		{
//			
//		}
		seive();
		int n=in.nextInt();
		for (int i=1;i<=1000;i++)
		{
			if (!prime[n*i+1])
			{
				out.println(i);
				break;
			}
		}
		out.close();
	}
	static int MAX=(int)1e6;
	static boolean prime[] = new boolean[MAX + 1];
	static void seive() {
		
		Arrays.fill(prime, true);
		for (int i = 2; i * i <= MAX; i++) {
			if (prime[i]) {
				for (int j = 2 * i; j <= MAX; j += i) {
					prime[j] = false;
				}
			}

		}
	}
}


class InputReader {
	public BufferedReader reader;
	public StringTokenizer tokenizer;

	public InputReader(InputStream inputstream) {
		reader = new BufferedReader(new InputStreamReader(inputstream));
		tokenizer = null;
	}

	public String nextLine() {
		String fullLine = null;
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				fullLine = reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			return fullLine;
		}
		return fullLine;
	}

	public String next() {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new StringTokenizer(reader.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	}

	public long nextLong() {
		return Long.parseLong(next());
	}
	
	public int[] nextIntArray(int n) {
		int a[] = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = nextInt();
		}
		return a;
	}
	
	public long[] nextLongArray(int n) {
		long a[] = new long[n];
		for (int i = 0; i < n; i++) {
			a[i] = nextLong();
		}
		return a;
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}
}

class OutputWriter {
	private final PrintWriter writer;

	public OutputWriter(OutputStream outputStream) {
		writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
	}

	public OutputWriter(Writer writer) {
		this.writer = new PrintWriter(writer);
	}

	public void print(Object... objects) {
		for (int i = 0; i < objects.length; i++) {
			if (i != 0)
				writer.print(' ');
			writer.print(objects[i]);
		}
	}

	public void println(Object... objects) {
		print(objects);
		writer.println();
	}

	public void close() {
		writer.close();
	}

	public void flush() {
		writer.flush();
	}
}