import java.util.*;
import java.io.*;

public class SherlocksArrayMergingAlgorithm {
    public static InputReader in;
    public static PrintWriter out;

    public static final int MAX = 1234;
    public static final int myMotivation = 0;    
    public static final int MOD = (int) 1e9 + 7;
    
    public static long[] fact = new long[MAX];
    public static long[][] ways = new long[MAX][MAX];

    public static void main(String[] args) {
	in = new InputReader(System.in);
	out = new PrintWriter(System.out);
	
	fact[0] = 1;
	for (int i = 1; i < MAX; i++) {
	    fact[i] = (i*fact[i - 1])%MOD;
	}
	
	ways[1][1] = 1;
	for(int i = 2; i < MAX; i++) {
	    ways[i][i] = 1;
	    for(int j = 1; j < i; j++) {
		ways[i][j] = add(mul(j, ways[i - 1][j - 1]), mul(fact[j], ways[i - j][j]));
	    }
	}
	
	
	int n = in.nextInt();
	int[] a = new int[n + 1];
	for (int i = 1; i <= n; i++) {
	    a[i] = in.nextInt();
	}
	
	long result = 0;
	for(int i = 1; i <= n; i++) {
	    result = (result + ways[n][i])%MOD;
	}
	out.println(result);

	out.close();
    }
    
    public static long add(long a, long b) {
	return (a + b)%MOD;
    }
    
    public static long mul(long a, long b) {
	return ((a%MOD)*(b%MOD))%MOD;
    }
    

    static class Node implements Comparable<Node> {
	int u, v;
	long score;

	public Node(int u, int v) {
	    this.u = u;
	    this.v = v;
	}

	public void print() {
	    System.out.println(u + " " + v + " " + score);
	}

	public int compareTo(Node that) {
	    return Long.compare(this.score, that.score);
	}
    }

    static class InputReader {

	private InputStream stream;
	private byte[] buf = new byte[8192];
	private int curChar, snumChars;
	private SpaceCharFilter filter;

	public InputReader(InputStream stream) {
	    this.stream = stream;
	}

	public int snext() {
	    if (snumChars == -1)
		throw new InputMismatchException();
	    if (curChar >= snumChars) {
		curChar = 0;
		try {
		    snumChars = stream.read(buf);
		} catch (IOException e) {
		    throw new InputMismatchException();
		}
		if (snumChars <= 0)
		    return -1;
	    }
	    return buf[curChar++];
	}

	public int nextInt() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    int sgn = 1;
	    if (c == '-') {
		sgn = -1;
		c = snext();
	    }
	    int res = 0;
	    do {
		if (c < '0' || c > '9')
		    throw new InputMismatchException();
		res *= 10;
		res += c - '0';
		c = snext();
	    } while (!isSpaceChar(c));
	    return res * sgn;
	}

	public long nextLong() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    int sgn = 1;
	    if (c == '-') {
		sgn = -1;
		c = snext();
	    }
	    long res = 0;
	    do {
		if (c < '0' || c > '9')
		    throw new InputMismatchException();
		res *= 10;
		res += c - '0';
		c = snext();
	    } while (!isSpaceChar(c));
	    return res * sgn;
	}

	public int[] nextIntArray(int n) {
	    int a[] = new int[n];
	    for (int i = 0; i < n; i++)
		a[i] = nextInt();
	    return a;
	}

	public String readString() {
	    int c = snext();
	    while (isSpaceChar(c))
		c = snext();
	    StringBuilder res = new StringBuilder();
	    do {
		res.appendCodePoint(c);
		c = snext();
	    } while (!isSpaceChar(c));
	    return res.toString();
	}

	public boolean isSpaceChar(int c) {
	    if (filter != null)
		return filter.isSpaceChar(c);
	    return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public interface SpaceCharFilter {
	    public boolean isSpaceChar(int ch);
	}
    }
}