#include <bits/stdc++.h>
using namespace std;
template <class T, size_t N>
ostream& operator<<(ostream& os, const array<T, N>& v);
template <class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  bool f = 1;
  os << "[";
  for (auto& i : v) {
    if (!f) os << ", ";
    os << i;
    f = 0;
  }
  return os << "]";
}
template <class T, size_t N>
ostream& operator<<(ostream& os, const array<T, N>& v) {
  bool f = 1;
  os << "[";
  for (auto& i : v) {
    if (!f) os << ", ";
    os << i;
    f = 0;
  }
  return os << "]";
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const set<T1, T2>& v) {
  bool f = 1;
  os << "[";
  for (auto& i : v) {
    if (!f) os << ", ";
    os << i;
    f = 0;
  }
  return os << "]";
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const multiset<T1, T2>& v) {
  bool f = 1;
  os << "[";
  for (auto& i : v) {
    if (!f) os << ", ";
    os << i;
    f = 0;
  }
  return os << "]";
}
template <class T1, class T2, class T3>
ostream& operator<<(ostream& os, const map<T1, T2, T3>& v) {
  bool f = 1;
  os << "[";
  for (auto& ii : v) {
    if (!f) os << ", ";
    os << "(" << ii.first << " -> " << ii.second << ") ";
    f = 0;
  }
  return os << "]";
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const multimap<T1, T2>& v) {
  bool f = 1;
  os << "[";
  for (auto& ii : v) {
    if (!f) os << ", ";
    os << "(" << ii.first << " -> " << ii.second << ") ";
    f = 0;
  }
  return os << "]";
}
template <class T1, class T2>
ostream& operator<<(ostream& os, priority_queue<T1, T2> v) {
  bool f = 1;
  os << "[";
  while (!v.empty()) {
    auto x = v.top();
    v.pop();
    if (!f) os << ", ";
    f = 0;
    os << x;
  }
  return os << "]";
}
template <class T1, class T2>
void printarray(const T1& a, T2 sz, T2 beg = 0) {
  for (T2 i = beg; i < sz; i++) cout << a[i] << " ";
  cout << endl;
}
void cio() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
}
void die() {
  printf("-1\n");
  exit(0);
}
int xx[4] = {1, -1, 0, 0}, yy[4] = {0, 0, 1, -1};
const long long mod = 1e9 + 7;
long long N, K;
long long dp[102][100500];
long long S[100500];
long long a[100500];
int main() {
  cio();
  cin >> N >> K;
  for (int i = 1; i <= N; i++) cin >> a[i];
  dp[0][0] = 1;
  S[0] = dp[0][0];
  for (int j = 1; j <= K; j++) S[j] = (S[j - 1] + dp[0][j]) % mod;
  for (int i = 1; i <= N; i++) {
    for (long long j = 0; j <= K; j++) {
      dp[i][j] = S[j] - ((j - a[i] - 1 < 0) ? 0 : S[j - a[i] - 1]);
    }
    S[0] = dp[i][0];
    for (int j = 1; j <= K; j++) S[j] = (S[j - 1] + dp[i][j]) % mod;
  }
  printf("%lld\n", dp[N][K]);
}
