#include #include #include using namespace std; int main(){ int m; cin >> m; int k; int cnt = 0; long long int sum = 0; double res = 1; while (cin >> k) { if (k == 0) { cout << "1" << endl; return 0; } sum += k; cnt++; } m = m - sum - cnt + 1; if (m < 0) { cout << "NA" << endl; return 0; } else { for (int i = 1; i <= cnt; i++) { res = (i + m)*(res/i); } } cout << (long long int)fmod(res,1000000007) << endl; return 0; }