#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <typename T>
using posteriority_queue = priority_queue<T, vector<T>, greater<T> >;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1},
          dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T &a, U b) {
  return a < b ? (a = b, true) : false;
}
template <typename T, typename U>
inline bool chmin(T &a, U b) {
  return a > b ? (a = b, true) : false;
}
template <typename T>
void unique(vector<T> &a) {
  a.erase(unique((a).begin(), (a).end()), a.end());
}
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;
int mod = MOD;
struct ModInt {
  unsigned val;
  ModInt() : val(0) {}
  ModInt(ll x) : val(x >= 0 ? x % mod : x % mod + mod) {}
  ModInt pow(ll exponent) {
    ModInt tmp = *this, res = 1;
    while (exponent > 0) {
      if (exponent & 1) res *= tmp;
      tmp *= tmp;
      exponent >>= 1;
    }
    return res;
  }
  ModInt &operator+=(const ModInt &x) {
    if ((val += x.val) >= mod) val -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &x) {
    if ((val += mod - x.val) >= mod) val -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &x) {
    val = static_cast<unsigned long long>(val) * x.val % mod;
    return *this;
  }
  ModInt &operator/=(const ModInt &x) {
    unsigned a = x.val, b = mod;
    int u = 1, v = 0;
    while (b) {
      unsigned tmp = a / b;
      swap(a -= tmp * b, b);
      swap(u -= tmp * v, v);
    }
    return *this *= u;
  }
  bool operator==(const ModInt &x) const { return val == x.val; }
  bool operator!=(const ModInt &x) const { return val != x.val; }
  bool operator<(const ModInt &x) const { return val < x.val; }
  bool operator<=(const ModInt &x) const { return val <= x.val; }
  bool operator>(const ModInt &x) const { return val > x.val; }
  bool operator>=(const ModInt &x) const { return val >= x.val; }
  ModInt &operator++() {
    if (++val == mod) val = 0;
    return *this;
  }
  ModInt operator++(int) {
    ModInt res = *this;
    ++*this;
    return res;
  }
  ModInt &operator--() {
    val = (val == 0 ? mod : val) - 1;
    return *this;
  }
  ModInt operator--(int) {
    ModInt res = *this;
    --*this;
    return res;
  }
  ModInt operator+() const { return *this; }
  ModInt operator-() const { return ModInt(val ? mod - val : 0); }
  ModInt operator+(const ModInt &x) const { return ModInt(*this) += x; }
  ModInt operator-(const ModInt &x) const { return ModInt(*this) -= x; }
  ModInt operator*(const ModInt &x) const { return ModInt(*this) *= x; }
  ModInt operator/(const ModInt &x) const { return ModInt(*this) /= x; }
  friend ostream &operator<<(ostream &os, const ModInt &x) {
    return os << x.val;
  }
  friend istream &operator>>(istream &is, ModInt &x) {
    ll val;
    is >> val;
    x = ModInt(val);
    return is;
  }
};
ModInt abs(const ModInt &x) { return x; }
struct Combinatorics {
  int val;
  vector<ModInt> fact, fact_inv, inv;
  Combinatorics(int val = 10000000)
      : val(val), fact(val + 1), fact_inv(val + 1), inv(val + 1) {
    fact[0] = 1;
    for (int i = (1); i < (val + 1); ++i) fact[i] = fact[i - 1] * i;
    fact_inv[val] = ModInt(1) / fact[val];
    for (int i = val; i > 0; --i) fact_inv[i - 1] = fact_inv[i] * i;
    for (int i = (1); i < (val + 1); ++i) inv[i] = fact[i - 1] * fact_inv[i];
  }
  ModInt nCk(int n, int k) {
    if (n < 0 || n < k || k < 0) return ModInt(0);
    return fact[n] * fact_inv[k] * fact_inv[n - k];
  }
  ModInt nPk(int n, int k) {
    if (n < 0 || n < k || k < 0) return ModInt(0);
    return fact[n] * fact_inv[n - k];
  }
  ModInt nHk(int n, int k) {
    if (n < 0 || k < 0) return ModInt(0);
    return (k == 0 ? ModInt(1) : nCk(n + k - 1, k));
  }
};
template <typename T>
function<vector<T>(const vector<T> &, const vector<T> &)> mul =
    [](const vector<T> &a, const vector<T> &b) {
      int n = a.size(), m = b.size();
      vector<T> res(n + m - 1, T(0));
      for (int i = (0); i < (n); ++i)
        for (int j = (0); j < (m); ++j) res[i + j] += a[i] * b[j];
      return res;
    };
template <typename T>
function<bool(const T &, T &)> sqr = [](const T &a, T &res) { return false; };
template <typename T>
struct FPS {
  vector<T> co;
  FPS(int deg = 0) : co(deg + 1, T(0)) {}
  FPS(const vector<T> &co) : co(co) {}
  FPS(initializer_list<T> init) : co(init.begin(), init.end()) {}
  template <typename InputIter>
  FPS(InputIter first, InputIter last) : co(first, last) {}
  inline const T &operator[](int term) const { return co[term]; }
  inline T &operator[](int term) { return co[term]; }
  void resize(int deg) {
    int prev = co.size();
    co.resize(deg + 1);
    if (prev < deg + 1) fill(co.begin() + prev, co.end(), T(0));
  }
  void shrink() {
    while (co.size() > 1 && co.back() == T(0)) co.pop_back();
  }
  int degree() const { return static_cast<int>(co.size()) - 1; }
  FPS &operator=(const vector<T> &new_co) {
    co.resize(new_co.size());
    copy((new_co).begin(), (new_co).end(), co.begin());
    return *this;
  }
  FPS &operator=(const FPS &x) {
    co.resize(x.co.size());
    copy((x.co).begin(), (x.co).end(), co.begin());
    return *this;
  }
  FPS &operator+=(const FPS &x) {
    int n = x.co.size();
    if (n > co.size()) resize(n - 1);
    for (int i = (0); i < (n); ++i) co[i] += x.co[i];
    return *this;
  }
  FPS &operator-=(const FPS &x) {
    int n = x.co.size();
    if (n > co.size()) resize(n - 1);
    for (int i = (0); i < (n); ++i) co[i] -= x.co[i];
    return *this;
  }
  FPS &operator*=(T x) {
    for (T &e : co) e *= x;
    return *this;
  }
  FPS &operator*=(const FPS &x) { return *this = mul<T>(co, x.co); }
  FPS &operator/=(T x) {
    assert(x != T(0));
    T inv_x = T(1) / x;
    for (T &e : co) e *= inv_x;
    return *this;
  }
  FPS &operator/=(const FPS &x) {
    if (x.co.size() > co.size()) return *this = FPS();
    int n = co.size() - x.co.size() + 1;
    FPS a(co.rbegin(), co.rbegin() + n),
        b(x.co.rbegin(), x.co.rbegin() + min(static_cast<int>(x.co.size()), n));
    b = b.inv(n - 1);
    a *= b;
    return *this = FPS(a.co.rend() - n, a.co.rend());
  }
  FPS &operator%=(const FPS &x) {
    *this -= *this / x * x;
    co.resize(static_cast<int>(x.co.size()) - 1);
    if (co.empty()) co = {T(0)};
    return *this;
  }
  FPS &operator<<=(int n) {
    co.insert(co.begin(), n, T(0));
    return *this;
  }
  FPS &operator>>=(int n) {
    if (co.size() < n) return *this = FPS();
    co.erase(co.begin(), co.begin() + n);
    return *this;
  }
  bool operator==(const FPS &x) const {
    FPS a(*this), b(x);
    a.shrink();
    b.shrink();
    int n = a.co.size();
    if (n != b.co.size()) return false;
    for (int i = (0); i < (n); ++i)
      if (a.co[i] != b.co[i]) return false;
    return true;
  }
  bool operator!=(const FPS &x) const { return !(*this == x); }
  FPS operator+() const { return *this; }
  FPS operator-() const {
    FPS res(*this);
    for (T &e : res.co) e = T(-e);
    return res;
  }
  FPS operator+(const FPS &x) const { return FPS(*this) += x; }
  FPS operator-(const FPS &x) const { return FPS(*this) -= x; }
  FPS operator*(T x) const { return FPS(*this) *= x; }
  FPS operator*(const FPS &x) const { return FPS(*this) *= x; }
  FPS operator/(T x) const { return FPS(*this) /= x; }
  FPS operator/(const FPS &x) const { return FPS(*this) /= x; }
  FPS operator%(const FPS &x) const { return FPS(*this) %= x; }
  FPS operator<<(int n) const { return FPS(*this) <<= n; }
  FPS operator>>(int n) const { return FPS(*this) >>= n; }
  T horner(T val) const {
    T res = T(0);
    for (int i = static_cast<int>(co.size()) - 1; i >= 0; --i)
      (res *= val) += co[i];
    return res;
  }
  FPS differential() const {
    int n = co.size();
    assert(n >= 1);
    FPS res(n - 1);
    for (int i = (1); i < (n); ++i) res.co[i - 1] = co[i] * T(i);
    return res;
  }
  FPS integral() const {
    int n = co.size();
    FPS res(n + 1);
    for (int i = (0); i < (n); ++i) res[i + 1] = co[i] / T(i + 1);
    return res;
  }
  FPS exp(int deg = -1) const {
    assert(co[0] == T(0));
    if (deg == -1) deg = static_cast<int>(co.size()) - 1;
    FPS one({T(1)}), res = one;
    for (int i = 1; i <= deg; i <<= 1) {
      res *= FPS(co.begin(),
                 co.begin() + min(static_cast<int>(co.size()), i << 1)) -
             res.log((i << 1) - 1) + one;
      res.co.resize(i << 1);
    }
    res.co.resize(deg + 1);
    return res;
  }
  FPS inv(int deg = -1) const {
    assert(co[0] != T(0));
    if (deg == -1) deg = static_cast<int>(co.size()) - 1;
    FPS res({T(1) / co[0]});
    for (int i = 1; i <= deg; i <<= 1) {
      res = res + res -
            res * res *
                FPS(co.begin(),
                    co.begin() + min(static_cast<int>(co.size()), i << 1));
      res.co.resize(i << 1);
    }
    res.co.resize(deg + 1);
    return res;
  }
  FPS log(int deg = -1) const {
    assert(co[0] == T(1));
    if (deg == -1) deg = static_cast<int>(co.size()) - 1;
    FPS integrand = differential() * inv(deg - 1);
    integrand.co.resize(deg);
    return integrand.integral();
  }
  FPS pow(ll exponent, int deg = -1) const {
    int n = co.size();
    if (deg == -1) deg = n - 1;
    for (int i = (0); i < (n); ++i) {
      if (co[i] != T(0)) {
        ll shift = exponent * i;
        if (shift > deg) break;
        T tmp = 1, base = co[i];
        ll e = exponent;
        while (e > 0) {
          if (e & 1) tmp *= base;
          base *= base;
          e >>= 1;
        }
        return ((((*this >> i) * (T(1) / co[i])).log(deg - shift) * T(exponent))
                    .exp(deg - shift) *
                tmp)
               << shift;
      }
    }
    return FPS(deg);
  }
  FPS mod_pow(ll exponent, const FPS &md) const {
    FPS inv_rev_md = FPS(md.co.rbegin(), md.co.rend()).inv();
    int deg_of_md = md.co.size();
    function<void(FPS &, const FPS &)> mod_mul = [&](FPS &multiplicand,
                                                     const FPS &multiplier) {
      multiplicand *= multiplier;
      if (deg_of_md <= multiplicand.co.size()) {
        int n = multiplicand.co.size() - deg_of_md + 1;
        FPS quotient =
            FPS(multiplicand.co.rbegin(), multiplicand.co.rbegin() + n) *
            FPS(inv_rev_md.co.begin(),
                inv_rev_md.co.begin() +
                    min(static_cast<int>(inv_rev_md.co.size()), n));
        multiplicand -= FPS(quotient.co.rend() - n, quotient.co.rend()) * md;
      }
      multiplicand.co.resize(deg_of_md - 1);
      if (multiplicand.co.empty()) multiplicand.co = {T(0)};
    };
    FPS res({T(1)}), base = *this;
    mod_mul(base, res);
    while (exponent > 0) {
      if (exponent & 1) mod_mul(res, base);
      mod_mul(base, base);
      exponent >>= 1;
    }
    return res;
  }
  FPS sqrt(int deg = -1) const {
    int n = co.size();
    if (deg == -1) deg = n - 1;
    if (co[0] == T(0)) {
      for (int i = (1); i < (n); ++i) {
        if (co[i] == T(0)) continue;
        if (i & 1) return FPS(-1);
        int shift = i >> 1;
        if (deg < shift) break;
        FPS res = (*this >> i).sqrt(deg - shift);
        if (res.co.empty()) return FPS(-1);
        res <<= shift;
        res.resize(deg);
        return res;
      }
      return FPS(deg);
    }
    T s;
    if (!sqr<T>(co[0], s)) return FPS(-1);
    FPS res({s});
    T half = T(1) / T(2);
    for (int i = 1; i <= deg; i <<= 1) {
      (res +=
       FPS(co.begin(), co.begin() + min(static_cast<int>(co.size()), i << 1)) *
       res.inv((i << 1) - 1)) *= half;
    }
    res.resize(deg);
    return res;
  }
  FPS translate(T c) const {
    int n = co.size();
    vector<T> fact(n, T(1)), inv_fact(n, T(1));
    for (int i = (1); i < (n); ++i) fact[i] = fact[i - 1] * T(i);
    inv_fact[n - 1] = T(1) / fact[n - 1];
    for (int i = n - 1; i > 0; --i) inv_fact[i - 1] = inv_fact[i] * T(i);
    vector<T> g(n), ex(n);
    for (int i = (0); i < (n); ++i) g[n - 1 - i] = co[i] * fact[i];
    T pow_c = T(1);
    for (int i = (0); i < (n); ++i) {
      ex[i] = pow_c * inv_fact[i];
      pow_c *= c;
    }
    vector<T> conv = mul<T>(g, ex);
    FPS res(n - 1);
    for (int i = (0); i < (n); ++i) res[i] = conv[n - 1 - i] * inv_fact[i];
    return res;
  }
};
namespace FFT {
using Real = long double;
struct Complex {
  Real re, im;
  Complex(Real re = 0, Real im = 0) : re(re), im(im) {}
  inline Complex operator+(const Complex &x) const {
    return Complex(re + x.re, im + x.im);
  }
  inline Complex operator-(const Complex &x) const {
    return Complex(re - x.re, im - x.im);
  }
  inline Complex operator*(const Complex &x) const {
    return Complex(re * x.re - im * x.im, re * x.im + im * x.re);
  }
  inline Complex mul_real(Real r) const { return Complex(re * r, im * r); }
  inline Complex mul_pin(Real r) const { return Complex(-im * r, re * r); }
  inline Complex conj() const { return Complex(re, -im); }
};
vector<int> butterfly{0};
vector<vector<Complex> > zeta{{{1, 0}}};
void calc(int n) {
  int prev_n = butterfly.size();
  if (n <= prev_n) return;
  butterfly.resize(n);
  int prev_lg = zeta.size(), lg = __builtin_ctz(n);
  for (int i = (1); i < (prev_n); ++i) butterfly[i] <<= lg - prev_lg;
  for (int i = (prev_n); i < (n); ++i)
    butterfly[i] = (butterfly[i >> 1] >> 1) | ((i & 1) << (lg - 1));
  zeta.resize(lg);
  for (int i = (prev_lg); i < (lg); ++i) {
    zeta[i].resize(1 << i);
    Real angle = -M_PI * 2 / (1 << (i + 1));
    for (int j = (0); j < (1 << (i - 1)); ++j) {
      zeta[i][j << 1] = zeta[i - 1][j];
      Real theta = angle * ((j << 1) + 1);
      zeta[i][(j << 1) + 1] = {cos(theta), sin(theta)};
    }
  }
}
void sub_dft(vector<Complex> &a) {
  int n = a.size();
  calc(n);
  int shift = __builtin_ctz(butterfly.size()) - __builtin_ctz(n);
  for (int i = (0); i < (n); ++i) {
    int j = butterfly[i] >> shift;
    if (i < j) swap(a[i], a[j]);
  }
  for (int block = 1; block < n; block <<= 1) {
    int den = __builtin_ctz(block);
    for (int i = 0; i < n; i += (block << 1))
      for (int j = (0); j < (block); ++j) {
        Complex tmp = a[i + j + block] * zeta[den][j];
        a[i + j + block] = a[i + j] - tmp;
        a[i + j] = a[i + j] + tmp;
      }
  }
}
template <typename T>
vector<Complex> dft(const vector<T> &a) {
  int sz = a.size(), lg = 1;
  while ((1 << lg) < sz) ++lg;
  vector<Complex> c(1 << lg);
  for (int i = (0); i < (sz); ++i) c[i].re = a[i];
  sub_dft(c);
  return c;
}
vector<Real> real_idft(vector<Complex> &a) {
  int n = a.size(), half = n >> 1, quarter = half >> 1;
  calc(n);
  a[0] = (a[0] + a[half] + (a[0] - a[half]).mul_pin(1)).mul_real(0.5);
  int den = __builtin_ctz(half);
  for (int i = (1); i < (quarter); ++i) {
    int j = half - i;
    Complex tmp1 = a[i] + a[j].conj(),
            tmp2 = ((a[i] - a[j].conj()) * zeta[den][j]).mul_pin(1);
    a[i] = (tmp1 - tmp2).mul_real(0.5);
    a[j] = (tmp1 + tmp2).mul_real(0.5).conj();
  }
  if (quarter > 0) a[quarter] = a[quarter].conj();
  a.resize(half);
  sub_dft(a);
  reverse(a.begin() + 1, a.end());
  Real r = 1.0 / half;
  vector<Real> res(n);
  for (int i = (0); i < (n); ++i)
    res[i] = (i & 1 ? a[i >> 1].im : a[i >> 1].re) * r;
  return res;
}
void idft(vector<Complex> &a) {
  int n = a.size();
  sub_dft(a);
  reverse(a.begin() + 1, a.end());
  Real r = 1.0 / n;
  for (int i = (0); i < (n); ++i) a[i] = a[i].mul_real(r);
}
template <typename T>
vector<Real> convolution(const vector<T> &a, const vector<T> &b) {
  int a_sz = a.size(), b_sz = b.size(), sz = a_sz + b_sz - 1, lg = 1;
  while ((1 << lg) < sz) ++lg;
  int n = 1 << lg;
  vector<Complex> c(n);
  for (int i = (0); i < (a_sz); ++i) c[i].re = a[i];
  for (int i = (0); i < (b_sz); ++i) c[i].im = b[i];
  sub_dft(c);
  int half = n >> 1;
  c[0] = Complex(c[0].re * c[0].im, 0);
  for (int i = (1); i < (half); ++i) {
    Complex i_square = c[i] * c[i], j_square = c[n - i] * c[n - i];
    c[i] = (j_square.conj() - i_square).mul_pin(0.25);
    c[n - i] = (i_square.conj() - j_square).mul_pin(0.25);
  }
  c[half] = Complex(c[half].re * c[half].im, 0);
  vector<Real> res = real_idft(c);
  res.resize(sz);
  return res;
}
};  // namespace FFT
vector<ModInt> mod_convolution(const vector<ModInt> &a, const vector<ModInt> &b,
                               const int pre = 15) {
  using Complex = FFT::Complex;
  int a_sz = a.size(), b_sz = b.size(), sz = a_sz + b_sz - 1, lg = 1;
  while ((1 << lg) < sz) ++lg;
  int n = 1 << lg;
  vector<Complex> A(n), B(n);
  for (int i = (0); i < (a_sz); ++i) {
    int ai = a[i].val;
    A[i] = Complex(ai & ((1 << pre) - 1), ai >> pre);
  }
  for (int i = (0); i < (b_sz); ++i) {
    int bi = b[i].val;
    B[i] = Complex(bi & ((1 << pre) - 1), bi >> pre);
  }
  FFT::sub_dft(A);
  FFT::sub_dft(B);
  int half = n >> 1;
  Complex tmp_a = A[0], tmp_b = B[0];
  A[0] = {tmp_a.re * tmp_b.re, tmp_a.im * tmp_b.im};
  B[0] = {tmp_a.re * tmp_b.im + tmp_a.im * tmp_b.re, 0};
  for (int i = (1); i < (half); ++i) {
    int j = n - i;
    Complex a_l_i = (A[i] + A[j].conj()).mul_real(0.5),
            a_h_i = (A[j].conj() - A[i]).mul_pin(0.5);
    Complex b_l_i = (B[i] + B[j].conj()).mul_real(0.5),
            b_h_i = (B[j].conj() - B[i]).mul_pin(0.5);
    Complex a_l_j = (A[j] + A[i].conj()).mul_real(0.5),
            a_h_j = (A[i].conj() - A[j]).mul_pin(0.5);
    Complex b_l_j = (B[j] + B[i].conj()).mul_real(0.5),
            b_h_j = (B[i].conj() - B[j]).mul_pin(0.5);
    A[i] = a_l_i * b_l_i + (a_h_i * b_h_i).mul_pin(1);
    B[i] = a_l_i * b_h_i + a_h_i * b_l_i;
    A[j] = a_l_j * b_l_j + (a_h_j * b_h_j).mul_pin(1);
    B[j] = a_l_j * b_h_j + a_h_j * b_l_j;
  }
  tmp_a = A[half];
  tmp_b = B[half];
  A[half] = {tmp_a.re * tmp_b.re, tmp_a.im * tmp_b.im};
  B[half] = {tmp_a.re * tmp_b.im + tmp_a.im * tmp_b.re, 0};
  FFT::idft(A);
  FFT::idft(B);
  vector<ModInt> res(sz);
  ModInt tmp1 = 1 << pre, tmp2 = 1LL << (pre << 1);
  for (int i = (0); i < (sz); ++i) {
    res[i] += static_cast<ll>(A[i].re + 0.5);
    res[i] += tmp1 * static_cast<ll>(B[i].re + 0.5);
    res[i] += tmp2 * static_cast<ll>(A[i].im + 0.5);
  }
  return res;
}
int main() {
  mul<ModInt> = [&](const vector<ModInt> &a, const vector<ModInt> &b) {
    return mod_convolution(a, b);
  };
  int n, k;
  cin >> n >> k;
  FPS<ModInt> fps(k);
  fps[0] = 1;
  while (n--) {
    int a;
    cin >> a;
    FPS<ModInt> child(k);
    for (int i = (0); i < (a + 1); ++i) child[i] = 1;
    fps *= child;
  }
  cout << fps[k] << '\n';
  return 0;
}
