#include <bits/stdc++.h>
using namespace std;
int f[101][100001], a[100001];
int main() {
  int i, n, j, k;
  scanf("%d%d", &n, &k);
  for (i = 1; i <= n; i++) scanf("%d", &a[i]);
  f[0][0] = 1;
  for (i = 0; i <= k; i++) f[0][i] = 1;
  for (i = 1; i <= n; i++) {
    for (j = 0; j <= k; j++) {
      f[i][j] = f[i - 1][j];
      if (j - a[i] - 1 >= 0)
        f[i][j] = (f[i][j] + 1000000007 - f[i - 1][j - a[i] - 1]) % 1000000007;
    }
    for (j = 1; j <= k; j++) f[i][j] = (f[i][j] + f[i][j - 1]) % 1000000007;
  }
  printf("%d", f[n][k] - f[n][k - 1]);
  return 0;
}
