#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;
using P   = pair<ll, ll>;
using mat = vector<vector<ll>>;

void IOS() { ios::sync_with_stdio(false), cin.tie(0); }

template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    fill((T *)array, (T *)(array + N), val);
}

const ll INF = 1e16;
const ll MOD = 1e9 + 7;
// int dx[4]    = {1, 0, -1, 0};
// int dy[4]    = {0, 1, 0, -1};
// ll pas[5001][5002];

ll dp[102][114514]  = {};
ll sum[102][114514] = {};

signed main() {
    IOS();
    ll n, k;
    cin >> n >> k;
    vector<ll> a(n);
    for (int i = 0; i < n; ++i) { cin >> a[i]; }
    sum[0][0] = 0;
    for (int i = 0; i <= k; ++i) {
        dp[0][i]      = (i <= a[0] ? 1 : 0);
        sum[0][i + 1] = sum[0][i] + dp[0][i];
    }
    for (int i = 1; i < n; ++i) {
        for (int j = 0; j <= k; ++j) {
            dp[i][j] =
                (sum[i - 1][j + 1] - sum[i - 1][max(0ll, j - a[i])]) % MOD;
            sum[i][j + 1] = (dp[i][j] + sum[i][j]) % MOD;
        }
    }
    cout << dp[n - 1][k] << endl;
}