#include <bits/stdc++.h>
using namespace std;
long long dp[110][100010];
int n, k;
int a[101];
int main() {
  cin >> n >> k;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 0; i <= n; i++) dp[i][0] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= a[i]; j++)
      dp[i][j] = (dp[i][j - 1] + dp[i - 1][j]) % 1000000007;
    for (int j = a[i] + 1; j <= k; j++)
      dp[i][j] =
          (dp[i][j - 1] + dp[i - 1][j] - dp[i - 1][j - a[i] - 1]) % 1000000007;
  }
  cout << dp[n][k];
  return 0;
}
