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


public class Main_yukicoder389 {

    public static void main(String[] args) {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    	Printer pr = new Printer(System.out);

		try {
			int m = Integer.parseInt(br.readLine());
			List<Integer> h = new ArrayList<>();
			int sum = 0;
			for (String s : br.readLine().split(" ")) {
				int tmp = Integer.parseInt(s);
				h.add(tmp);
				sum += tmp;
			}

			preCombi2(1_000_000);

			int k = h.size();
			if (sum == 0) {
				k = 0;
			}

			pr.println(C(m - sum - (k - 1) + k, k));
		} catch (NumberFormatException e) {
			// TODO 自動生成された catch ブロック
			e.printStackTrace();
		} catch (IOException e) {
			// TODO 自動生成された catch ブロック
			e.printStackTrace();
		}

        pr.close();
    }

	private static int MOD = 1_000_000_007;
	private static long[] fact;
	private static long[] ifact;

	private static void preCombi2(int size) {
		// cache size need size * 2 * 16.
		fact = new long[size + 1];
		fact[0] = 1;
		for (int i = 1; i <= size; i++) {
			fact[i] = fact[i - 1] * i % MOD;
		}

		ifact = new long[size + 1];
		ifact[0] = 1;

		int loop = MOD - 2;
		long x = fact[size];
		ifact[size] = 1;
		while (loop > 0) {
			if (loop % 2 == 1) {
				ifact[size] = ifact[size] * x % MOD;
			}
			x = x * x % MOD;
			loop /= 2;
		}

		for (int i = size - 1; i >= 0; i--) {
			ifact[i] = ifact[i + 1] * (i + 1) % MOD;
		}
	}

	private static int C(int n, int r) {
		if (r > n) {
			return 0;
		}

		return (int)(((fact[n] * ifact[n - r]) % MOD) * ifact[r] % MOD);
	}

	@SuppressWarnings("unused")
	private static int P(int n, int r) {
		if (r > n) {
			return 0;
		}

		return (int)((fact[n] * ifact[n -r]) % MOD);
	}

	@SuppressWarnings("unused")
	private static int H(int n, int r) {
		if (n == 0 && r == 0) {
			return 1;
		}

		return C(n + r - 1, r);
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}