#include <bits/stdc++.h>
#define int long long int
using namespace std;
int power(int x, int y, int p)
{
    int res = 1;     // Initialize result

    x = x % p; // Update x if it is more than or
                // equal to p

    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = (res*x) % p;

        // y must be even now
        y = y>>1; // y = y/2
        x = (x*x) % p;
    }
    return res;
}
int mod = 1000000007;
signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int n,m;
    cin>>n>>m;
    int s= 0 ;
    for(int i = 1;i<= n;i++){
        int z;
        cin>>z;
        s+= z;
    }
    if(m<s ){
        cout<<"0\n";return 0 ;
    }
    int ans = 1;
    for(int i =m - s+1 ;i<=n+m;i++  ){
        ans*= i;
        ans%= mod;
    }
    for(int i = 1;i<= n+s;i++){
        ans = ans*(power(i , mod-2 , mod ) );
        ans%= mod;
    }
    cout<<ans;
}
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
string to_string(string s) { return '"' + s + '"'; }
string to_string(const char* s) { return to_string(string(s)); }
string to_string(bool b) { return to_string(int(b)); }
string to_string(vector<bool>::reference b) { return to_string(int(b)); }
string to_string(char b) { return "'" + string(1, b) + "'"; }
template <typename A, typename B>
string to_string(pair<A, B> p) { return "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; }
template <typename A>
string to_string(A v) {
	string res = "{";
	for (const auto& x : v) res += (res == "{" ? "" : ", ") + to_string(x);
	return res + "}";
}
void debug() { cerr << endl; }
template <typename Head, typename... Tail>
void debug(Head H, Tail... T) {
	cerr << " " << to_string(H);
	debug(T...);
}
#define db(...) cerr << "[" << #__VA_ARGS__ << "]:", debug(__VA_ARGS__)
#else
#define db(...) 42
#endif
typedef long long ll;
typedef long double ld;
const int MOD = 1000000007;
struct Mint {
	int val;
	Mint() { val = 0; }
	Mint(const ll& x) {
		val = (-MOD <= x && x < MOD) ? x : x % MOD;
		if (val < 0) val += MOD;
	}
	template <typename U>
	explicit operator U() const { return (U)val; }
	friend bool operator==(const Mint& a, const Mint& b) { return a.val == b.val; }
	friend bool operator!=(const Mint& a, const Mint& b) { return !(a == b); }
	friend bool operator<(const Mint& a, const Mint& b) { return a.val < b.val; }
	Mint& operator+=(const Mint& m) { if ((val += m.val) >= MOD) val -= MOD; return *this; }
	Mint& operator-=(const Mint& m) { if ((val -= m.val) < 0) val += MOD; return *this; }
	Mint& operator*=(const Mint& m) { val = (ll)val * m.val % MOD; return *this; }
	friend Mint modex(Mint a, ll p) {
		assert(p >= 0);
		Mint ans = 1;
		for (; p; p >>= 1, a *= a) if (p & 1) ans *= a;
		return ans;
	}
	Mint& operator/=(const Mint& m) { return *this *= modex(m, MOD - 2); }
	Mint& operator++() { return *this += 1; }
	Mint& operator--() { return *this -= 1; }
	Mint operator++(int) { Mint result(*this); *this += 1; return result; }
	Mint operator--(int) { Mint result(*this); *this -= 1; return result; }
	Mint operator-() const { return Mint(-val); }
	friend Mint operator+(Mint a, const Mint& b) { return a += b; }
	friend Mint operator-(Mint a, const Mint& b) { return a -= b; }
	friend Mint operator*(Mint a, const Mint& b) { return a *= b; }
	friend Mint operator/(Mint a, const Mint& b) { return a /= b; }
	friend ostream& operator<<(ostream& os, const Mint& x) { return os << x.val; }
	friend string to_string(const Mint& b) { return to_string(b.val); }
};
int main() {
	int n, m;
	scanf("%d%d", &n, &m);
	int s = 0;
	for (int i = 0; i < n; ++i) {
		int a;
		scanf("%d", &a);
		s += a;
	}
	m += n;
	s += n;
	Mint ans = 1;
	for (int i = 0; i < s; ++i) {
		ans *= m - i;
		ans /= i + 1;
	}
	printf("%d\n", ans.val);
}
