#include <bits/stdc++.h>

#define rep(i, n) for(int i = 0; i<(n); i++)
#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
using namespace std;
using ll = long long;

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 1000000007;

struct mint {
    ll x; // typedef long long ll;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}

    mint operator-() const { return mint(-x); }

    mint &operator+=(const mint a) {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }

    mint &operator-=(const mint a) {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }

    mint &operator*=(const mint a) {
        (x *= a.x) %= mod;
        return *this;
    }

    mint operator+(const mint a) const {
        mint res(*this);
        return res += a;
    }

    mint operator-(const mint a) const {
        mint res(*this);
        return res -= a;
    }

    mint operator*(const mint a) const {
        mint res(*this);
        return res *= a;
    }

    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const {
        return pow(mod - 2);
    }

    mint &operator/=(const mint a) {
        return (*this) *= a.inv();
    }

    mint operator/(const mint a) const {
        mint res(*this);
        return res /= a;
    }
};

// Binary Indexed Tree (Fenwick Tree)
// https://youtu.be/lyHk98daDJo?t=7960
template<typename T>
struct BIT {
    int n;
    vector<T> d;

    BIT(int n = 0) : n(n), d(n + 1) {}

    void add(int i, T x = 1) {
        for (i++; i <= n; i += i & -i) {
            d[i] += x;
        }
    }

    T sum(int i) {
        T x = 0;
        for (i++; i; i -= i & -i) {
            x += d[i];
        }
        return x;
    }
};

BIT<mint> dp[110];

int main() {
    int N, K;
    cin >> N >> K;
    vector<int> a(N);
    rep(i, N) cin >> a[i];

    rep(i, N + 1) dp[i] = BIT<mint>(K + 1);
    dp[0].add(0, 1);
    rep(i, N) {
        rep(j, K + 1) {
            mint now = dp[i].sum(j);
            int low = j - a[i] - 1;
            if (low >= 0) now -= dp[i].sum(low);
            dp[i + 1].add(j, now);
        }
    }
    cout << (dp[N].sum(K) - dp[N].sum(K - 1)).x << endl;
}