#include <bits/stdc++.h>
using namespace std;
const int N(105), K(133333);
int a[N], s[K];
long long dp[N][K];
int n, k;
int main() {
  cin >> n >> k;
  for (int i = 0; i < n; ++i) cin >> a[i];
  for (int j = 0; j <= k; ++j) dp[0][j] = 0;
  for (int j = 0; j <= n; ++j) dp[j][0] = 1;
  for (int i = 1; i <= n; ++i) {
    s[0] = 0;
    for (int j = 1; j <= k + 1; j++) s[j] = s[j - 1] + dp[i - 1][j - 1];
    for (int j = 1; j <= k; j++) {
      dp[i][j] = s[j + 1] - s[max(0, j - a[i - 1])];
      dp[i][j] = dp[i][j] % 1000000007;
    }
  }
  cout << dp[n][k];
  return 0;
}
