#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int dp[101][100005], n;
int a[101], k;
signed main() {
  cin >> n >> k;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
  }
  dp[0][0] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j <= k; j++) {
      dp[i][j] = dp[i - 1][j];
      if (j) dp[i][j] += dp[i][j - 1];
      if (j - a[i] - 1 >= 0)
        dp[i][j] = (dp[i][j] + mod - dp[i - 1][j - a[i] - 1]) % mod;
      dp[i][j] %= mod;
    }
  }
  cout << dp[n][k] << endl;
  return 0;
}
