#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int,int>;

#define ff first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()

const int M = 1e9+7;
const int inf = 1e9;
const int mx  = 1e7+5;

ll a[mx], f[mx];
ll power(ll x, ll p){
    ll ans = 1;
    while(p > 0){
        if(p & 1) ans = (ans * x) % M;
        x = (x * x) % M; p >>= 1;
    }return ans;
}

ll inv(ll x){return power(x,M-2);}
ll ncr(ll x, ll y){
    if(y > x) return 0;

    ll ans = 1;
    for(ll r=1; r<=y; r++){
        ans = (ans * (x - r + 1)) % M;
        ans = (ans * inv(r)) % M;
    }return ans;
}

void solve(int cs){
//    cout << "Case " << cs << ": ";

    f[0] = 1;
    for(int i=1; i<mx; i++)
        f[i] = (i * 1LL * f[i-1]) % M;

    ll n, m; cin >> n >> m; ll sum = n;
    for(int i=0; i<n; i++)
        cin >> a[i], sum += a[i];
    cout << ncr(m+n, sum) << "\n";
}

int main(){

    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    int tc = 1, cs = 1;
//    cin >> tc;
    while(tc--) solve(cs++);

    return 0;
}


#pragma GCC optimize("Ofast")
#pragma GCC target ("sse4")

#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acosl(-1.0);

ll mod_pow(ll x, ll n, ll m = mod) {
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
struct modint {
	ll n;
	modint() :n(0) { ; }
	modint(ll m) :n(m) {
		if (n >= mod)n %= mod;
		else if (n < 0)n = (n % mod + mod) % mod;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 17;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}



void solve() {
	int n, m; cin >> n >>m;
	vector<int> a(n);
	int sum = 0;
	rep(i, n) {
		cin >> a[i]; sum += a[i];
	}
	if (sum > m) {
		cout << 0 << "\n"; return;
	}
	modint ans = 1;
	int ad = n;
	//(m+n,sum+n)
	rep1(i, sum + n) {
		ans = ans*(modint)(m + n + 1 - i);
		ans = ans / (modint)(i);
	}
	cout << ans << "\n";
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(15);
	//init_f();
	//init();
	//expr();
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}