/*
 * (a1+a2+...)!/(a1!*a2!*...)
 */
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.Scanner;


public class Main {//把大数用到极致了
	public static void main(String[] args) {
		Scanner input=new Scanner(new InputStreamReader(System.in));
		int n;
		while((n=input.nextInt())!=0){
			int a[]=new int[n];
			long sum=0;
			for(int i=0;i<n;i++){
				a[i]=input.nextInt();
				sum+=a[i];
			}
			BigInteger a1=NUM(sum);
			BigInteger s=BigInteger.ONE;
			for(int i=0;i<n;i++){
				s=s.multiply(NUM(a[i]));
			}
		//	System.out.println(a1+"   "+s);
			System.out.println(a1.divide(s));
		}
	}

	private static BigInteger NUM(long sum) {//计算阶乘
		BigInteger sum1=BigInteger.ONE;
		for(int i=2;i<=sum;i++)
			sum1=sum1.multiply(BigInteger.valueOf(i));
		return sum1;
	}
}