#include <bits/stdc++.h>
using namespace std;
const long long N = 1e6 + 5, inf = 1e18, mod = 1e9 + 7;
const long double pi = 3.141592653589793238;
bool check_prime(long long n) {
  long long flag = 0, i;
  for (i = 2; i * i <= n; i++) {
    if (n % i == 0) {
      flag = 1;
      break;
    }
  }
  if (n == 1) {
    return false;
  } else if (flag == 0 || n == 2 || n == 3) {
    return true;
  } else {
    return false;
  }
}
long long fastexpo(long long a, long long b, long long MOD) {
  long long result = 1;
  while (b > 0) {
    if (b % 2 == 1) {
      result = (result * a) % MOD;
    }
    a = (a * a) % MOD;
    b = b / 2;
  }
  return result;
}
long long a[105];
long long dp[105][100005];
long long solve(long long n, long long k) {
  if (k < 0) {
    return 0;
  }
  if (dp[n][k] != -1) {
    return dp[n][k];
  }
  long long ans;
  if (n > 0 && k > 0) {
    ans =
        (solve(n - 1, k) + solve(n, k - 1) - solve(n - 1, k - 1 - a[n])) % mod;
  } else {
    if (k <= a[n]) {
      ans = 1;
    } else {
      ans = 0;
    }
  }
  dp[n][k] = ans;
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long N, K, i, j;
  cin >> N >> K;
  for (i = 0; i < N; i++) {
    cin >> a[i];
  }
  for (i = 0; i < 105; i++) {
    for (j = 0; j < 100005; j++) {
      dp[i][j] = -1;
    }
  }
  cout << solve(N - 1, K) << "\n";
  return 0;
}
