// [3/17/2015 JmingS]
/*
此题可直接推导出公式：
{（A1+A2+……+An）!} / {A1!A2!……An!}
由于 （12×26）! = 312! 只能通过数组来存储，所以又涉及『大数乘法』和『大数除法』，
大数实现的主要思想模拟手算，具体参考程序。
*/
1 #include <iostream>
2 #include <cstdlib>
3 #include <cstdio>
4 #include <cstring>
5 using namespace std;
6 const int MAX = 800;
7
8 int n, arr[30];
9 int total;
10 int Ans[MAX], len;
11
12 // 阶乘
13 void Factorial(int _n, int _arr[], int &_len) {
14 for (int num = 2; num <= _n; ++num) {
15 int cnt = 0, val, carry = 0;
16 for (; cnt < _len; ++cnt) {
17 val = _arr[cnt] * num + carry;
18 _arr[cnt] = val % 10;
19 carry = val / 10;
20 }
21 while (carry) {
22 _arr[_len++] = carry % 10;
23 carry /= 10;
24 }
25 }
26 }
27
28 // 大数除法
29 void Div(int data) {
30 int carry = 0;
31 int val;
32 for (int i = len - 1; i >= 0; --i) {
33 val = Ans[i] + carry * 10;
34 Ans[i] = val / data;
35 carry = val%data;
36 }
37 while (0 == Ans[len - 1]) {
38 --len;
39 }
40 }
41
42 void Solve() {
43 for (int i = 0; i < n; ++i) {
44 for (int j = 2; j <= arr[i]; ++j) {
45 Div(j);
46 }
47 }
48 }
49
50 int main()
51 {
52 //freopen("input.txt", "r", stdin);
53 //freopen("output.txt", "w", stdout);
54 while (~scanf("%d", &n) && n) {
55 total = 0;
56 for (int i = 0; i < n; ++i) {
57 scanf("%d", &arr[i]);
58 total += arr[i];
59 }
60 Ans[0] = 1;
61 len = 1;
62 Factorial(total, Ans, len);
63 Solve();
64 for (int i = len - 1; i >= 0; --i) {
65 printf("%d", Ans[i]);
66 }
67 printf("\n");
68 }
69 return 0;
70 }
