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

public class Main {
    static FastScanner in;
    static int n;
    static final int MOD = 1000000007;

    public static void main(String[] args) throws IOException {
        //        System.setOut(new PrintStream(new BufferedOutputStream(new FileOutputStream("nocross.out")), true));
        in = new FastScanner(System.in);
        //        in = new FastScanner("nocross.in");
        //        in = new FastScanner("input.txt");
        n = in.nextInt();
        int[] m = new int[n];
        for (int i = 0; i < n; i++) {
            m[i] = in.nextInt();
        }
        long f[] = new long[1201];
        f[1] = 1;
        f[2] = 2;
        for (int i = 3; i <= 1200; i++) {
            f[i] = 2;
            for (int j = 2; j <= i - 1; j++) {
                f[i] += f[i - j] * j;
                f[i] = f[i] % MOD;
            }
        }
        long ans = 1;
        int cur = 1;
        for (int i = 0; i < n - 1; i++) {
            if (m[i] > m[i + 1]) {
                break;
            }
            cur++;
        }
        ans *= f[cur];
        ans = ans % MOD;
        System.out.println(ans);
    }
}

class FastScanner {

    BufferedReader br;
    StringTokenizer tokenizer;

    FastScanner(String fileName) throws FileNotFoundException {
        this(new FileInputStream(new File(fileName)));
    }

    FastScanner(InputStream is) {
        br = new BufferedReader(new InputStreamReader(is));
    }

    String nextLine() throws IOException {
        tokenizer = null;
        return br.readLine();
    }

    String next() throws IOException {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            String line = br.readLine();
            if (line == null) {
                return null;
            }
            tokenizer = new StringTokenizer(line);
        }
        return tokenizer.nextToken();
    }

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

    long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    char nextChar() throws IOException {
        return next().charAt(0);
    }
}