#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 105;
const int MAX_K = 100005;
const int MOD = 1000000007;
int n, k, a[MAX_N];
int dp[MAX_N][MAX_K], sum[MAX_K];
int main() {
  scanf("%d %d", &n, &k);
  for (int i = 1; i <= n; i++) scanf("%d", a + i);
  dp[0][0] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= k + 1; j++)
      sum[j] = (sum[j - 1] + dp[i - 1][j - 1]) % MOD;
    for (int j = 0; j <= k; j++) dp[i][j] = sum[j + 1] - sum[max(0, j - a[i])];
  }
  printf("%d\n", dp[n][k]);
  return 0;
}
