#include <bits/stdc++.h>
using namespace std;
long long add(long long a, long long b, long long c) {
  long long res = a + b;
  return (res >= c ? res - c : res);
}
long long mod_neg(long long a, long long b, long long c) {
  long long res;
  if (abs(a - b) < c)
    res = a - b;
  else
    res = (a - b) % c;
  return (res < 0 ? res + c : res);
}
long long mul(long long a, long long b, long long c) {
  long long res = (long long)a * b;
  return (res >= c ? res % c : res);
}
template <typename T>
T power(T e, T n) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = x * p;
    p = p * p;
    n >>= 1;
  }
  return x;
}
template <typename T>
T mdpower(T e, T n, T m) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = mul(x, p, m);
    p = mul(p, p, m);
    n >>= 1;
  }
  return x;
}
template <typename T>
T extended_euclid(T a, T b, T &x, T &y) {
  T xx = 0, yy = 1;
  y = 0;
  x = 1;
  while (b) {
    T q = a / b, t = b;
    b = a % b;
    a = t;
    t = xx;
    xx = x - q * xx;
    x = t;
    t = yy;
    yy = y - q * yy;
    y = t;
  }
  return a;
}
template <typename T>
T mod_inverse(T a, T n) {
  T x, y, z = 0;
  T d = extended_euclid(a, n, x, y);
  return (d > 1 ? -1 : mod_neg(x, z, n));
}
const long long N = 101;
const long long M = 100005;
long long dp[N][M];
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, k;
  cin >> n >> k;
  vector<long long> v(n + 1);
  for (long long i = 1; i <= n; i++) cin >> v[i];
  for (long long i = 0; i <= n; i++) dp[i][0] = 1;
  for (long long i = 1; i <= n; i++) {
    long long length = v[i] + 1;
    long long sum = 0;
    for (long long j = 0; j < length; j++) {
      sum = (sum % 1000000007 + dp[i - 1][j] % 1000000007) % 1000000007;
      dp[i][j] = sum;
    }
    for (long long j = length; j <= k; j++)
      dp[i][j] = (sum % 1000000007 + dp[i - 1][j] % 1000000007 -
                  dp[i - 1][j - length] % 1000000007 + 1000000007) %
                 1000000007;
  }
  cout << dp[n][k] << "\n";
  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
