#include <bits/stdc++.h>
using namespace std;
const int NMAX = 1e2 + 11;
const int KMAX = 1e5 + 11;
const int MOD = 1e9 + 7;
int n, k, a[NMAX], acc[KMAX], dp[NMAX][KMAX];
int solve(void) {
  dp[0][0] = 1;
  for (int s = 1; s <= k; ++s) dp[0][s] = 0;
  for (int i = 1; i <= n; ++i) {
    acc[0] = dp[i - 1][0];
    for (int s = 1; s <= k; ++s) acc[s] = (acc[s - 1] + dp[i - 1][s]) % MOD;
    for (int s = 0; s <= k; ++s)
      dp[i][s] = (acc[s] - (s - a[i] - 1 >= 0 ? acc[s - a[i] - 1] : 0)) % MOD;
  }
  return dp[n][k];
}
int main(void) {
  cin >> n >> k;
  for (int i = 1; i <= n; ++i) cin >> a[i];
  cout << solve() << endl;
  return 0;
}
