#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<string.h>

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define NDEBUG
#define eprintf(...) do {} while (0)
#endif
#include<cassert>

using namespace std;

typedef long long LL;
typedef vector<int> VI;

#define REP(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define EACH(i,c) for(__typeof((c).begin()) i=(c).begin(),i##_end=(c).end();i!=i##_end;++i)

template<class T> inline void amin(T &x, const T &y) { if (y<x) x=y; }
template<class T> inline void amax(T &x, const T &y) { if (x<y) x=y; }
#define rprintf(fmt, begin, end) do { const auto end_rp = (end); auto it_rp = (begin); for (bool sp_rp=0; it_rp!=end_rp; ++it_rp) { if (sp_rp) putchar(' '); else sp_rp = true; printf(fmt, *it_rp); } putchar('\n'); } while(0)

template<unsigned MOD_> struct ModInt {
    static constexpr unsigned MOD = MOD_;
    unsigned x;
    void undef() { x = (unsigned)-1; }
    bool isnan() const { return x == (unsigned)-1; }
    inline int geti() const { return (int)x; }
    ModInt() { x = 0; }
    ModInt(int y) { if (y<0 || (int)MOD<=y) y %= (int)MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt(long long y) { if (y<0 || MOD<=y) y %= MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned long long y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt &operator+=(const ModInt y) { if ((x += y.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(const ModInt y) { if ((x -= y.x) & (1u<<31)) x += MOD; return *this; }
    ModInt &operator*=(const ModInt y) { x = (unsigned long long)x * y.x % MOD; return *this; }
    ModInt &operator/=(const ModInt y) { x = (unsigned long long)x * y.inv().x % MOD; return *this; }
    ModInt operator-() const { return (x ? MOD-x: 0); }

    ModInt inv() const { return pow(MOD-2); }
    ModInt pow(long long y) const {
	ModInt b = *this, r = 1;
	if (y < 0) { b = b.inv(); y = -y; }
	for (; y; y>>=1) {
	    if (y&1) r *= b;
	    b *= b;
	}
	return r;
    }

    friend ModInt operator+(ModInt x, const ModInt y) { return x += y; }
    friend ModInt operator-(ModInt x, const ModInt y) { return x -= y; }
    friend ModInt operator*(ModInt x, const ModInt y) { return x *= y; }
    friend ModInt operator/(ModInt x, const ModInt y) { return x *= y.inv(); }
    friend bool operator<(const ModInt x, const ModInt y) { return x.x < y.x; }
    friend bool operator==(const ModInt x, const ModInt y) { return x.x == y.x; }
    friend bool operator!=(const ModInt x, const ModInt y) { return x.x != y.x; }
};

constexpr LL MOD = 1000000007;
using Mint = ModInt<MOD>;

int N;
LL M;
LL A[2011];

void MAIN() {
    scanf("%d%lld", &N, &M);
    REP (i, N) scanf("%lld", A+i);

    LL sum = 0;
    REP (i, N) sum += A[i];
    if (sum > M) {
	puts("0");
	return;
    }

    Mint nu = 1;
    Mint de = 1;
    REP (a, sum+N) {
	de *= a+1;
	nu *= M+N-a;
    }

    Mint ans = nu / de;


    printf("%d\n", ans.geti());
}

int main() {
    int TC = 1;
//    scanf("%d", &TC);
    REP (tc, TC) MAIN();
    return 0;
}


#include <bits/stdc++.h>
using namespace std;

template<int MAX>
struct Combination {
    vector<long long> _inv, _fac, _ifac;
    const long long MOD;
    Combination(long long mod) : _inv(MAX+1), _fac(MAX+1), _ifac(MAX+1), MOD(mod) { init(); }
    void init() { init_inv(), init_fac(); }

    void init_inv() {
        _inv[0] = 0;
        for (int i = 1; i <= MAX; i++) {
            if (i == 1) _inv[i] = 1;
            else {
                _inv[i] = (MOD - (MOD / i) * _inv[MOD % i]) % MOD;
                if (_inv[i] < 0) _inv[i] += MOD;
            }
        }
    }
    void init_fac() {
        _fac[0] = _ifac[0] = 1;
        for (int i = 1; i <= MAX; i++) {
            _fac[i] = _fac[i-1] * i % MOD;
            _ifac[i] = _ifac[i-1] * _inv[i] % MOD;
        }
    }

    long long modpow(long long n, long long r) {
        n %= MOD, r %= (MOD-1);
        if (!n) return 0;
        long long ret = 1; long long tmp = n;
        while (r != 0) {
            if (r % 2) ret *= tmp;
            tmp *= tmp; tmp %= MOD; ret %= MOD;
            r /= 2;
        }
        return ret;
    }
    long long invb(int i) { return (i <= MAX) ? _inv[i] : this->modpow(i, MOD-2); }
    long long inv(int i) const { return _inv[i]; }
    long long fac(int i) const { return _fac[i]; }
    long long ifac(int i) const { return _ifac[i]; }

    long long operator()(int n, int r) const {
        if (n < r) return 0;
        return fac(n) * ifac(r) % MOD * ifac(n-r) % MOD;
    }
};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int N, M; cin >> N >> M;
    constexpr long long mod = 1000000007;
    Combination<5000000> C(mod);
    long long Ans = 1;
    vector<int> A(N);
    int S = 0;
    for (auto &x: A) {
        cin >> x; S += x;
    }
    for (int i = 1; i <= N + S; i++) {
        Ans = Ans * C.invb(i) % mod;
        Ans = Ans * (M + N + 1 - i) % mod;
    }
    cout << Ans << "\n";
    return 0;
}