#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvi = vector<vi>;
using vvl = vector<vl>;
const int INF = 1 << 28;
const ll MOD = 1000000007;
template <class T>
bool chmax(T &a, const T &b) {
    return (a < b) ? (a = b, 1) : 0;
}
template <class T>
bool chmin(T &a, const T &b) {
    return (b < a) ? (a = b, 1) : 0;
}

struct mint {
    ll v;
    ll mod;
    mint() : v(0) {}
    mint(signed v, ll mod = MOD) : v(v), mod(mod) {}
    mint(ll t, ll mod = MOD) : mod(mod) {
        v = t % mod;
        if (v < 0)
            v += mod;
    }

    mint pow(ll k) {
        mint res(1), tmp(v);
        while (k) {
            if (k & 1)
                res *= tmp;
            tmp *= tmp;
            k >>= 1;
        }
        return res;
    }

    static mint add_identity() { return mint(0); }
    static mint mul_identity() { return mint(1); }

    mint inv() { return pow(mod - 2); }

    mint &operator+=(mint a) {
        v += a.v;
        if (v >= mod)
            v -= mod;
        return *this;
    }
    mint &operator-=(mint a) {
        v += mod - a.v;
        if (v >= mod)
            v -= mod;
        return *this;
    }
    mint &operator*=(mint a) {
        v = 1LL * v * a.v % mod;
        return *this;
    }
    mint &operator/=(mint a) { return (*this) *= a.inv(); }

    mint operator+(mint a) const { return mint(v) += a; };
    mint operator-(mint a) const { return mint(v) -= a; };
    mint operator*(mint a) const { return mint(v) *= a; };
    mint operator/(mint a) const { return mint(v) /= a; };

    mint operator-() const { return v ? mint(MOD - v) : mint(v); }

    bool operator==(const mint a) const { return v == a.v; }
    bool operator!=(const mint a) const { return v != a.v; }
    bool operator<(const mint a) const { return v < a.v; }
};

template <typename T = int>
struct BinaryIndexedTree {
    int n;
    vector<T> bit;
    BinaryIndexedTree(int n_, T init = 0) : n(n_), bit(n_ + 1, init) {}
    BinaryIndexedTree(vector<T> init) : n(init.size() + 1), bit(init.size() + 1) {
        for (int i = 1; i < init.size() + 1; ++i) {
            bit[i] = init[i - 1];
        }
    }
    T sum(int i) {
        T s = bit[0];
        for (int x = i; x > 0; x -= (x & -x))
            s += bit[x];
        return s;
    }
    void add(int i, T a) {
        if (i == 0)
            return;
        for (int x = i; x <= n; x += (x & -x))
            bit[x] += a;
    }
    int lower_bound(int w) {
        if (w <= 0)
            return 0;
        int x = 0, r = 1;
        while (r < n)
            r <<= 1;
        for (int k = r; k > 0; k >>= 1) {
            if (x + k <= n && bit[x + k] < w) {
                w -= bit[x + k];
                x += k;
            }
        }
        return x + 1;
    }
    T query(int l, int r) { return sum(r - 1) - sum(l - 1); }
};

int main() {
    int n, k;
    cin >> n >> k;
    vl a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    vector<BinaryIndexedTree<mint>> bit(n + 1, BinaryIndexedTree<mint>(k + 2));
    bit[0].add(1, 1);

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= k + 1; ++j) {
            bit[i].add(j, bit[i - 1].query(max(1LL, j - a[i - 1]), j + 1));
        }
    }
    cout << bit[n].query(k + 1, k + 2).v << endl;
    return 0;
}

Measured memory_bytes: 159744