#include <bits/stdc++.h>
using namespace std;
using P = pair<int64_t, int64_t>;
using mat = vector<vector<int64_t>>;
void IOS() { ios::sync_with_stdio(false), cin.tie(0); }
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}
const int64_t INF = 1e16;
const int64_t MOD = 1e9 + 7;
int64_t dp[102][114514] = {};
int64_t sum[102][114514] = {};
signed main() {
  IOS();
  int64_t n, k;
  cin >> n >> k;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  sum[0][0] = 0;
  for (int i = 0; i <= k; ++i) {
    dp[0][i] = (i <= a[0] ? 1 : 0);
    sum[0][i + 1] = sum[0][i] + dp[0][i];
  }
  for (int i = 1; i < n; ++i) {
    for (int j = 0; j <= k; ++j) {
      dp[i][j] = (sum[i - 1][j + 1] - sum[i - 1][max(0, j - a[i])]) % MOD;
      sum[i][j + 1] = (dp[i][j] + sum[i][j]) % MOD;
    }
  }
  cout << dp[n - 1][k] << endl;
}
