#include
    
     using namespace std;long long int C[100][100] = {}, A[20][100] = {};const long long int mod = 1e9 + 7;void init() {    C[0][0] = 1;    for (int i = 1; i < 90; ++i) {        C[i][0] = C[i][i] = 1;        for (int j = 1; j < i; ++j) {            C[i][j] = C[i - 1][j - 1] + C[i - 1][j];            C[i][j] = C[i][j] >= mod ? C[i][j] - mod : C[i][j];        }    }}long long int F(int x,int target, int t,int cnt) {    long long int cnt0 = cnt - t,ans=0;    for (int i = 0; i < t; ++i) {        int tt = t - i,targett=target-i;        if (targett <= x) ans+=  C[x][x - targett] * C[cnt0 - x][tt - (x - targett)] * C[t-1][i];    }    return ans;}int main() {    init();    int k,t;    cin >> k;    int cnt = 1;    A[0][0] =1;    for (int i = 1; i <= k;++i) {        cin >> t;        cnt += t;        for (int j = 0; j <= cnt; ++j) {            for (int idx = max(0,j-t); idx <= j + t; ++idx) {                if(A[i-1][idx])                    A[i][j] = (A[i][j]+A[i - 1][idx]*F(idx, j,t,cnt))%mod;            }            if (j == 0 && i == k) {                cout << A[k][0];                return 0;            }        }    }}