#include <bits/stdc++.h>
using namespace std;
int n, k;
int dp[110][100009];
int s[110][100009];
const int mod = 1e9 + 7;
int main() {
  scanf("%d%d", &n, &k);
  dp[0][k] = s[0][k] = 1;
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    for (int j = 1; j <= k; j++)
      dp[i][j] = (s[i - 1][min(x, j + x)] - s[i - 1][j - 1] + mod) % mod;
    s[i][0] = dp[i][0] = s[i - 1][x];
    for (int j = 1; j <= k; j++) s[i][j] = (s[i][j - 1] + dp[i][j]) % mod;
  }
  cout << dp[n][0] << endl;
  return 0;
}
