#ifdef LOCAL
#pragma GCC optimize ("O0")
#else
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target ("avx")
#endif

#include <vector>
#include <set>
#include <map>
#include <tuple>
#include <queue>
#include <stack>
#include <bitset>
#include <functional>
#include <algorithm>
#include <utility>
#include <numeric>
#include <iostream>
#include <cmath>
#include <cassert>

using namespace std;

using ll = long long;
using VI = vector<int>;
using VVI = vector<vector<int>>;
using VLL = vector<ll>;
using VVLL = vector<vector<ll>>;
using VB = vector<bool>;
using PII = pair<int, int>;
using PLL = pair<ll, ll>;
template <typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;
const int INF = 1000000007;
const ll INF_LL = 1'000'000'000'000'000'007;

#define __overload3(_1, _2, _3, name,...) name
#define rep(...) __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name##__LINE__, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until) for (int name = from, name##__until = (until); name < name##__until; name++)
#define repr(...) __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until) for (int name = until - 1, name##__from = (from); name >= name##__from; name--)

#define EXIT(out) do { OUT(out); exit(0); } while (0)

#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define _1 first
#define _2 second

#ifdef LOCAL
#define debug(v) do {debugos << "L" << __LINE__ << " " << #v << " > ";debugos<<(v)<<newl;} while (0)
#define debugv(v) do {debugos << "L" << __LINE__ << " " << #v << " > ";for(auto e:(v)){debugos<<e<<" ";}debugos<<newl;} while (0)
#define debuga(m,w) do {debugos << "L" << __LINE__ << " " << #m << " > ";for(int x=0;x<(w);x++){debugos<<(m)[x]<<" ";}debugos<<newl;} while (0)
#define debugaa(m,h,w) do {debugos << "L" << __LINE__ << " " << #m << " > \n";for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){debugos<<(m)[y][x]<<" ";}debugos<<newl;}} while (0)
#else
#define debug(v) do {v;} while (0)
#define debugv(v) do; while (0)
#define debuga(m,w) do; while (0)
#define debugaa(m,h,w) do; while (0)
#endif

#define newl "\n"
constexpr int dr[] = {1,-1,0,0};  // LRUD
constexpr int dc[] = {0,0,1,-1};

bool inside(int r, int c, int H, int W) {
  return 0 <= r and r < H and 0 <= c and c < W;
}

template <typename T> bool chmin(T& var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else return false;
}

template <typename T> bool chmax(T& var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else return false;
}

template <typename T> int sgn(T val) { return (T(0) < val) - (val < T(0)); }

ll power(ll e, int t, ll mod = INF_LL) {
  ll res = 1;
  while (t) {
    if (t&1) res = (res * e) % mod;
    t >>= 1;
    e = (e * e) % mod;
  }
  return res;
}

template <typename T> T divceil(T, T);

template <typename T> T divfloor(T m, T d) {
  if (sgn(m) * sgn(d) >= 0) return m / d;
  else return -divceil(abs(m), abs(d));
}

template <typename T> T divceil(T m, T d) {
  if (m >= 0 and d > 0) return (m+d-1)/d;
  else if (m < 0 and d < 0) return divceil(-m, -d);
  else return -divfloor(abs(m), abs(d));
}

template<typename T>
vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }

template<typename... Ts>
auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}

string operator*(const string& s, int times) {
  string res = "";
  rep(times) res += s;
  return res;
}

class MyScanner {
public:
  int offset = 0;
  char nc(){
    static char buf[100000],*L=buf,*R=buf;
    return L==R&&(R=(L=buf)+fread(buf,1,100000,stdin),L==R)?EOF:*L++;
  }
  template <typename T> void input_integer(T& var) {
    var = 0; T sign = 1;
    int cc = nc();
    for (; cc<'0' || '9'<cc; cc = nc())
      if (cc == '-') sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = nc())
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign; var += offset;
  }
  int c() { char c; while (c = nc(), c == ' ' or c == '\n'); return c; }
  MyScanner& operator>>(char& var) { var = c(); return *this; }
  MyScanner& operator>>(int& var) { input_integer<int>(var); return *this; }
  MyScanner& operator>>(ll& var) { input_integer<ll>(var); return *this; }
  MyScanner& operator>>(string& var) {
    var = ""; int cc = nc();
    for (; !isvisiblechar(cc); cc = nc());
    for (; isvisiblechar(cc); cc = nc())
      var.push_back(cc);
    return *this;
  }
  template <typename T>
  operator T() { T x; *this >> x; return x; }
  template <typename T>
  void operator()(T &t) { *this >> t; }
  template <typename T, typename... Ts>
  void operator()(T &t, Ts &...ts) { *this >> t; this->operator()(ts...); }
  template <typename Iter>
  void iter(Iter first, Iter last) { while (first != last) *this >> *first, first++; }
  VI vi(int n) { VI res(n); iter(all(res)); return res; }
  VVI vvi(int n, int m) { VVI res(n); rep(i, n) res[i] = vi(m); return res; }
  VLL vll(int n) { VLL res(n); iter(all(res)); return res; }
  VVLL vvll(int n, int m) { VVLL res(n); rep(i, n) res[i] = vll(m); return res; }
  template <typename T>
  vector<T> v(int n) { vector<T> res(n); iter(all(res)); return res; }
private:
  int isvisiblechar(int c) { return 0x21 <= c && c <= 0x7E; }
} IN, IN1{-1};

class MyPrinter {
public:
  template <typename T>
  void output_integer(T var) {
    if (var == 0) { putchar('0'); return; }
    if (var < 0) putchar('-'), var = -var;
    char stack[32]; int stack_p = 0;
    while (var) stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p) putchar(stack[--stack_p]);
  }
  MyPrinter& operator<<(char c) { putchar(c); return *this; }
  MyPrinter& operator<<(double x) { printf("%.10f\n", x); return *this; }
  template <typename T> MyPrinter& operator<<(T var) { output_integer<T>(var); return *this; }
  MyPrinter& operator<<(char* str_p) { while (*str_p) putchar(*(str_p++)); return *this; }
  MyPrinter& operator<<(const char* str_p) { while (*str_p) putchar(*(str_p++)); return *this; }
  MyPrinter& operator<<(const string& str) {
    const char* p = str.c_str();
    const char* l = p + str.size();
    while (p < l) putchar(*p++);
    return *this;
  }
  template <typename T>
  void operator()(T x) { *this << x << newl; }
  template <typename T, typename... Ts>
  void operator()(T x, Ts ...xs) { *this << x << " "; this->operator()(xs...); }
  template <typename Iter>
  void iter(Iter s, Iter t) {
    if (s == t) *this << "\n";
    else {
      for (; s != t; s++) {
        *this << *s << " \n"[next(s, 1) == t];
      }
    }
  }
  template <typename Range>
  void range(const Range& r) { iter(begin(r), end(r)); }
} OUT;

class DebugPrint {
public:
  template <typename T>
  DebugPrint& operator <<(const T& v) {
#ifdef LOCAL
    cerr << v;
#endif
    return *this;
  }
} debugos;

template <typename OutStream, typename T, typename U>
OutStream& operator<<(OutStream& out, pair<T, U> var) {
  return out << var.first << " " << var.second;
}
template <typename OutStream, typename Tuple, size_t I, size_t N,
          enable_if_t<I == N>* = nullptr>
OutStream& tuple_impl(OutStream& out, Tuple var) {
  return out;
}
template <typename OutStream, typename Tuple, size_t I, size_t N,
          enable_if_t<I != N>* = nullptr>
OutStream& tuple_impl(OutStream& out, Tuple var) {
  out << get<I>(var) << " ";
  return tuple_impl<Tuple, I+1, N>(out, var);
}
template <typename OutStream, typename... Ts>
OutStream& operator<<(OutStream& out, tuple<Ts...> var) {
  return tuple_impl<tuple<Ts...>, 0, sizeof...(Ts)>(out, var);
}
template <typename InStream, typename T, typename U>
InStream& operator>>(InStream& in, pair<T, U>& var) {
  return in >> var.first >> var.second;
}
template <typename InStream, typename... Ts>
InStream& operator>>(InStream& in, tuple<Ts...>& var) {
  return tuple_impl<tuple<Ts...>, 0, sizeof...(Ts)>(in, var);
}
template <typename InStream, typename Tuple, size_t I, size_t N,
          enable_if_t<I == N>* = nullptr>
InStream& tuple_impl(InStream& in, Tuple& var) {
  return in;
}
template <typename InStream, typename Tuple, size_t I, size_t N,
          enable_if_t<I != N>* = nullptr>
InStream& tuple_impl(InStream& in, Tuple& var) {
  in >> get<I>(var);
  return tuple_impl<Tuple, I+1, N>(in, var);
}


template <ll> class modint;
template <ll MOD> constexpr modint<MOD> pow(modint<MOD>, size_t);
template <ll MOD> class modint {
 public:
  ll value;

  constexpr modint(const ll x = 0) noexcept : value(x) {
    value %= MOD;
    if (value < 0) value += MOD;
  }
  constexpr bool operator==(const modint<MOD>& rhs) {
    return value == rhs.value;
  }
  constexpr bool operator!=(const modint<MOD>& rhs) {
    return value != rhs.value;
  }
  constexpr modint<MOD> operator-() const { return modint<MOD>(0) - *this; }
  constexpr modint<MOD> operator+(const modint<MOD>& rhs) const {
    return modint<MOD>(*this) += rhs;
  }
  constexpr modint<MOD> operator-(const modint<MOD>& rhs) const {
    return modint<MOD>(*this) -= rhs;
  }
  constexpr modint<MOD> operator*(const modint<MOD>& rhs) const {
    return modint<MOD>(*this) *= rhs;
  }
  constexpr modint<MOD> operator/(const modint<MOD>& rhs) const {
    return modint<MOD>(*this) /= rhs;
  }
  constexpr modint<MOD>& operator+=(const modint<MOD>& rhs) {
    value += rhs.value;
    if (value >= MOD) value -= MOD;
    return *this;
  }
  constexpr modint<MOD>& operator-=(const modint<MOD>& rhs) {
    if (value < rhs.value) value += MOD;
    value -= rhs.value;
    return *this;
  }
  constexpr modint<MOD>& operator*=(const modint<MOD>& rhs) {
    value = value * rhs.value % MOD;
    return *this;
  }
  constexpr modint<MOD>& operator/=(const modint<MOD>& rhs) {
    return *this *= pow(rhs, MOD - 2);
  }
  constexpr modint<MOD>& operator++() { return *this += 1; }
  constexpr modint<MOD> operator++(int) {
    modint<MOD> tmp(*this);
    ++(*this);
    return tmp;
  }
  constexpr modint<MOD>& operator--() { return *this -= 1; }
  constexpr modint<MOD> operator--(int) {
    modint<MOD> tmp(*this);
    --(*this);
    return tmp;
  }
  constexpr operator int() const { return (int)value; }
  constexpr operator ll() const { return value; }
};

template <ll MOD>
MyPrinter& operator<<(MyPrinter& out, modint<MOD> n) {
  out << n.value;
  return out;
}
template <ll MOD>
DebugPrint& operator<<(DebugPrint& out, modint<MOD> n) {
  out << n.value;
  return out;
}

template <ll MOD>
constexpr modint<MOD> pow(modint<MOD> base, size_t exp) {
  modint<MOD> res = 1;
  while (exp) {
    if (exp % 2) res *= base;
    base *= base;
    exp /= 2;
  }
  return res;
}

// O(r + log MOD)
template <ll MOD>
modint<MOD> choose(int n, int r) {
  chmin(r, n - r);
  if (r < 0) return modint<MOD>(0);
  modint<MOD> nu = 1, de = 1;
  rep(i, r) nu *= n - i, de *= i + 1;
  return nu / de;
}
constexpr ll bmds(int x) {
  const ll v[] = {1012924417, 924844033, 998244353, 897581057, 645922817};
  return v[x];
}
constexpr int brts(int x) { // primitive roots
  const int v[] = {5, 5, 3, 3, 3};
  return v[x];
}
template <int X>
struct NTT {
  static constexpr int md = bmds(X);
  static constexpr int rt = brts(X);
  using M = modint<md>;
  vector<vector<M> > rts, rrts;

  void ensure_base(int n) {
    if ((int)rts.size() >= n) return;
    rts.resize(n);
    rrts.resize(n);
    for (int i = 1; i < n; i <<= 1) {
      if (!rts[i].empty()) continue;
      M w = pow(M(rt), (md - 1) / (i << 1));
      M rw = M(1) / w;
      rts[i].resize(i);
      rrts[i].resize(i);
      rts[i][0] = M(1);
      rrts[i][0] = M(1);
      for (int k = 1; k < i; k++) {
        rts[i][k] = rts[i][k - 1] * w;
        rrts[i][k] = rrts[i][k - 1] * rw;
      }
    }
  }

  void ntt(vector<M>& as, bool f) {
    int n = as.size();
    assert((n & (n - 1)) == 0);
    ensure_base(n);

    for (int i = 0, j = 1; j + 1 < n; j++) {
      for (int k = n >> 1; k > (i ^= k); k >>= 1)
        ;
      if (i > j) swap(as[i], as[j]);
    }

    for (int i = 1; i < n; i <<= 1) {
      for (int j = 0; j < n; j += i * 2) {
        for (int k = 0; k < i; k++) {
          M z = as[i + j + k] * (f ? rrts[i][k] : rts[i][k]);
          as[i + j + k] = as[j + k] - z;
          as[j + k] += z;
        }
      }
    }

    if (f) {
      M tmp = M(1) / M(n);
      for (int i = 0; i < n; i++) as[i] *= tmp;
    }
  }

  vector<M> multiply(vector<M> as, vector<M> bs) {
    int need = as.size() + bs.size() - 1;
    int sz = 1;
    while (sz < need) sz <<= 1;
    as.resize(sz, M(0));
    bs.resize(sz, M(0));

    ntt(as, 0);
    ntt(bs, 0);
    for (int i = 0; i < sz; i++) as[i] *= bs[i];
    ntt(as, 1);

    as.resize(need);
    return as;
  }

  vector<int> multiply(vector<int> as, vector<int> bs) {
    vector<M> am(as.size()), bm(bs.size());
    for (int i = 0; i < (int)am.size(); i++) am[i] = M(as[i]);
    for (int i = 0; i < (int)bm.size(); i++) bm[i] = M(bs[i]);
    vector<M> cm = multiply(am, bm);
    vector<int> cs(cm.size());
    for (int i = 0; i < (int)cs.size(); i++) cs[i] = cm[i].value;
    return cs;
  }
};

struct Garner {
  using ll = long long;
  static NTT<0> ntt0;
  static NTT<1> ntt1;
  static NTT<2> ntt2;

  static constexpr int pow(int a, int b, int md) {
    int res = 1;
    a = a % md;
    while (b) {
      if (b & 1) res = (ll)res * a % md;
      a = (ll)a * a % md;
      b >>= 1;
    }
    return res;
  }

  static constexpr int inv(int x, int md) { return pow(x, md - 2, md); }

  inline void garner(int &c0, int c1, int c2, int m01, int mod) {
    static constexpr int r01 = inv(ntt0.md, ntt1.md);
    static constexpr int r02 = inv(ntt0.md, ntt2.md);
    static constexpr int r12 = inv(ntt1.md, ntt2.md);

    c1 = (ll)(c1 - c0) * r01 % ntt1.md;
    if (c1 < 0) c1 += ntt1.md;

    c2 = (ll)(c2 - c0) * r02 % ntt2.md;
    c2 = (ll)(c2 - c1) * r12 % ntt2.md;
    if (c2 < 0) c2 += ntt2.md;

    c0 %= mod;
    c0 += (ll)c1 * ntt0.md % mod;
    if (c0 >= mod) c0 -= mod;
    c0 += (ll)c2 * m01 % mod;
    if (c0 >= mod) c0 -= mod;
  }

  inline void garner(vector<vector<int>> &cs, int mod) {
    int m01 = (ll)ntt0.md * ntt1.md % mod;
    int sz = cs[0].size();
    for (int i = 0; i < sz; i++) garner(cs[0][i], cs[1][i], cs[2][i], m01, mod);
  }

  vector<int> multiply(vector<int> as, vector<int> bs, int mod) {
    vector<vector<int>> cs(3);
    cs[0] = ntt0.multiply(as, bs);
    cs[1] = ntt1.multiply(as, bs);
    cs[2] = ntt2.multiply(as, bs);
    size_t sz = as.size() + bs.size() - 1;
    for (auto &v : cs) v.resize(sz);
    garner(cs, mod);
    return cs[0];
  }

  template <typename T>
  decltype(auto) multiply(vector<T> am, vector<T> bm) {
    vector<int> as(am.size()), bs(bm.size());
    for (int i = 0; i < (int)as.size(); i++) as[i] = am[i].v;
    for (int i = 0; i < (int)bs.size(); i++) bs[i] = bm[i].v;
    vector<int> cs = multiply(as, bs, T::mod);
    vector<T> cm(cs.size());
    for (int i = 0; i < (int)cm.size(); i++) cm[i] = T(cs[i]);
    return cm;
  }
} garner;
NTT<0> Garner::ntt0;
NTT<1> Garner::ntt1;
NTT<2> Garner::ntt2;


int main() {
  int n = IN, k = IN;
  VI res = {1};
  rep(n) {
    int a = IN;
    VI f(a+1, 1);
    res = garner.multiply(res, f, 1'000'000'007);
    res.resize(k+1);
  }
  OUT(res[k]);
}