#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define Pint pair<int,int>
#define Pll pair<ll,ll>
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<n;i++)
#define all(v) v.begin(),v.end()
#define pb push_back
#define eb emplace_back
template<class T>void chmax(T &a,T b){if(a<b)a=b;}
template<class T>void chmin(T &a,T b){if(a>b)a=b;}
constexpr int INF=1000000000;
constexpr ll llINF=1000000000000000000;
constexpr int mod=1000000007;
constexpr double eps=1e-8;
const double pi=acos(-1);
int dx[]={0,1,0,-1},dy[]={1,0,-1,0};
int Random(int mi,int ma){
    random_device rnd;
    mt19937 mt(rnd());//32bit
    //[mi,ma]
    uniform_int_distribution<int>engine(mi,ma);
    return engine(mt);
}
ll gcd(ll a,ll b){
    if(b==0)return a;
    return gcd(b,a%b);
}
ll lcm(ll a,ll b){
    return a/gcd(a,b)*b;
}
bool prime(int a){
    if(a==1)return false;
    for(int i=2;i*i<=a;i++){
        if(a%i==0)return false;
    }
    return true;
}
ll modpow(ll a,ll b){
    if(b==0)return 1;
    if(b%2)return modpow(a,b-1)*a%mod;
    ll memo=modpow(a,b/2);
    return memo*memo%mod;
}
vector<ll>kaijo,invkaijo;
void init_fact(int n){
    kaijo.resize(n+1);
    invkaijo.resize(n+1);
    kaijo[0]=1;
    for(ll i=1;i<=n;i++){
        kaijo[i]=kaijo[i-1]*i;
        kaijo[i]%=mod;
    }
    rep(i,n+1)invkaijo[i]=modpow(kaijo[i],mod-2);
}
vector<vector<ll>>C,sC;
void init_comb(int n,int m){
    C.resize(n+1,vector<ll>(m+1,0));
    sC.resize(n+1,vector<ll>(m+1,0));
    C[0][0]=1;
    for(int i=1;i<=n;i++){
        C[i][0]=1;
        for(int j=1;j<=m;j++){
            C[i][j]=(C[i-1][j-1]+C[i-1][j])%mod;
        }
    }
    rep(i,n+1){
        rep(j,m){
            sC[i][j+1]=(sC[i][j]+C[i][j])%mod;
        }
    }
}
ll comb(int a,int b){
    if(a<b)return 0;
    if(a<0)return 0;
    return kaijo[a]*invkaijo[a-b]%mod*invkaijo[b]%mod;
}
ll inv(ll x){
    x=modpow(x,mod-2);
    return x;
}
int n,a[2121];
ll m;
int main(){
    cin>>n>>m;
    ll s=0;
    rep(i,n){
        cin>>a[i];
        s+=a[i];
    }
    int x=n+m;
    int y=s+n;
    ll ans=1;
    for(int i=x;i>x-y;i--){
        ans*=i;
        ans%=mod;
    }
    for(int i=1;i<=y;i++){
        ans*=inv(i);
        ans%=mod;
    }
    cout<<ans<<endl;
    return 0;
}
//DUEL
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define x first
#define y second
#define pii pair<int,int>
#define pb push_back
#define eb emplace_back
#pragma GCC optimize("unroll-loops")
#define shandom_ruffle(a, b) shuffle(a, b, rng)
#define vi vector<int>
#define vl vector<ll>
#define popcnt __builtin_popcount
#define popcntll __builtin_popcountll
#define all(a) begin(a),end(a)

using namespace std;
using namespace __gnu_pbds;

using ll=long long;
using ull=unsigned long long;
using ld=long double;
const int MOD=1000000007;
vector<int> bases;
const ll LLINF=1ll<<60;
const char en='\n';

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void yes() {cout<<"YES"<<en; exit(0);}
void no() {cout<<"NO"<<en; exit(0);}
inline int rund() {int x576363482791fuweh=rng();return abs(x576363482791fuweh)%RAND_MAX;}
template<class T>
void prVec(vector<T> w,bool fl=false)
{
	cout<<w.size()<<en;
	for (int i=0;i<int(w.size())-1;++i) cout<<w[i]<<' ';
	if (w.size()) cout<<w[w.size()-1]<<en;
	if (fl) cout<<flush;
}

ll raand()
{
	ll a=rund();
	a*=RAND_MAX;
	a+=rund();
    return a;
}

#define rand raand

ll raaand()
{
	return raand()*(MOD-7)+raand();
}

void compress(vi&v)
{
	set<int> s;
	for (auto a: v) s.insert(a);
	vi o(all(s));
	for (auto&a: v) a=lower_bound(all(o),a)-o.begin();
}

void compress(vl&v)
{
	set<ll> s;
	for (auto a: v) s.insert(a);
	vl o(all(s));
	for (auto&a: v) a=lower_bound(all(o),a)-o.begin();
}

string to_upper(string a)
{
	for (int i=0;i<(int)a.size();++i) if (a[i]>='a' && a[i]<='z') a[i]-='a'-'A';
	return a;
}

string to_lower(string a)
{
	for (int i=0;i<(int)a.size();++i) if (a[i]>='A' && a[i]<='Z') a[i]+='a'-'A';
	return a;
}

ll sti(string a,int base=10)
{
	ll k=0;
	for (int i=0;i<(int)a.size();++i)
	{
		k*=base;
		k+=a[i]-'0';
	}
	return k;
}

template<class T>
void eras(vector<T>& a,T b)
{
	a.erase(find(a.begin(),a.end(),b));
}

string its(ll k,int base=10)
{
	if (k==0) return "0";
	string a;
	while (k)
	{
		a.push_back((k%base)+'0');
		k/=base;
	}
	reverse(a.begin(),a.end());
	return a;
}

ll min(ll a,int b)
{
	if (a<b) return a;
	return b;
}

ll min(int a,ll b)
{
	if (a<b) return a;
	return b;
}

ll max(ll a,int b)
{
	if (a>b) return a;
	return b;
}

ll max(int a,ll b)
{
	if (a>b) return a;
	return b;
}

ll gcd(ll a,ll b)
{
	if (b==0) return a;
	return gcd(b,a%b);
}

ll lcm(ll a,ll b)
{
	return a/gcd(a,b)*b;
}

template<class T,class K>
pair<T,K> mp(T a,K b)
{
	return make_pair(a,b);
}

inline int mult(ll a,ll b)
{
	return (a*b)%MOD;
}

inline int pot(int n,int k)
{
	if (k==0) return 1;
	ll a=pot(n,k/2);
	a=mult(a,a);
	if (k%2) return mult(a,n);
	else return a;
}

int divide(int a,int b)
{
	return mult(a,pot(b,MOD-2));
}

inline int sub(int a,int b)
{
	if (a-b>=0) return a-b;
	return a-b+MOD;
}

inline int add(int a,int b)
{
	if (a+b>=MOD) return a+b-MOD;
	return a+b;
}

bool prime(ll a)
{
	if (a==1) return 0;
	for (int i=2;i<=round(sqrt(a));++i)
	{
		if (a%i==0) return 0;
	}
	return 1;
}

int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
const int N=300010;
int n,m;

ll co(int a,int b)
{
	ll re=1;
	for (int i=a;i>a-b;--i)
	{
		re=mult(re,i);
		re=divide(re,a+1-i);
	}
	return re;
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	for (int i=0;i<10;++i) bases.push_back(rand()%(MOD-13893829*2)+13893829);
	cin>>n>>m;
	ll s=0;
	for (int i=0;i<n;++i)
	{
		int a;
		cin>>a;
		s+=a;
	}
	cout<<co(m+n,s+n)<<en;
}





