#include <algorithm>
#include <cstdint>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, s, t) for (int i = s; i < t; i++)
#define ALL(obj) obj.begin(), obj.end()
#define fcout cout << fixed << setprecision(10)
const int iINF = 1e9;
const long long llINF = 1e18;
const int MOD = 1e9 + 7;
template <class T>
inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}

struct mint {
    long long x;
    mint(long long 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 { return mint(*this) += a; }
    mint operator-(const mint a) const { return mint(*this) -= a; }
    mint operator*(const mint a) const { return mint(*this) *= a; }
    mint pow(long long t) const {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    mint inv() const { return pow(MOD - 2); }
    mint& operator/=(const mint a) { return *this *= a.inv(); }
    mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
long long extGCD(long long a, long long b, long long& x, long long& y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }

    long long d = extGCD(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

long long gcd(long long a, long long b) {
    if (b == 0) {
        return a;
    } else {
        return gcd(b, a % b);
    }
}

long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }

template <typename T>
map<T, int> compress(vector<T> x) {
    map<T, int> res;
    sort(x.begin(), x.end());
    x.erase(unique(x.begin(), x.end()), x.end());
    for (int i = 0; i < x.size(); i++) {
        res[x[i]] = i;
    }

    return res;
}

template <typename T>
int former(const vector<T>& v, T x) {
    return upper_bound(v.begin(), v.end(), x) - v.begin() - 1;
}

template <typename T>
int latter(const vector<T>& v, T x) {
    return lower_bound(v.begin(), v.end(), x) - v.begin();
}

template <typename T>
using vec = vector<T>;
template <typename T>
using vvec = vector<vector<T>>;
using ll = long long;

using Pli = pair<long long, int>;
using Pll = pair<long long, long long>;

int main() {
    int N, K;
    cin >> N >> K;
    vec<int> A(N);
    REP(i, N) cin >> A[i];
    vec<mint> dp(K + 1, 0);
    dp[0] = 1;
    for (auto a : A) {
        for (int i = dp.size() - 1; i >= a + 1; i--) dp[i] -= dp[i - (a + 1)];
    }

    REP(_, N) { REP(i, K) dp[i + 1] += dp[i]; }
    cout << dp[K] << endl;
    return 0;
}

Measured memory_bytes: 1024