///17571@nith.ac.in @Ankit Verma
#include <bits/stdc++.h>
using namespace std;
#define ff          first
#define ss          second
#define pb          push_back
#define MP          make_pair
#define int         long long
#define ll          long long
#define inf         0x3f3f3f3f
#define MOD         1000000007
#define ld          long double
#define eb          emplace_back
#define pii         pair<int,int>
#define ull         unsigned long long
#define all(v)      v.begin(), v.end()
#define f(i,x,n)    for(int i=x;i<n;i++)
#define fr(i,x,n)   for(int i=x;i>=n;i--)
#define fastio      ios::sync_with_stdio(false)

#define n_l '\n'
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; } template<typename T> int SIZE(const T &t) { return t.size(); } string to_string(const string s, int x1 = 0, int x2 = 1e9) { return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"'; } string to_string(const char* s) { return to_string((string) s); } string to_string(const bool b) { return (b ? "true" : "false"); } string to_string(const char c) { return string({c}); } template<size_t N> string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) { string t = ""; for (int __iii__ = min(x1, SIZE(b)),  __jjj__ = min(x2, SIZE(b) - 1); __iii__ <= __jjj__; ++__iii__) { t += b[__iii__] + '0'; } return '"' + t + '"'; } template <typename A, typename... C> string to_string(const A (&v), int x1 = 0, int x2 = 1e9, C... coords); int l_v_l_v_l = 0, t_a_b_s = 0; template <typename A, typename B> string to_string(const pair<A, B> &p) { l_v_l_v_l++; string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; l_v_l_v_l--; return res; } template <typename A, typename... C> string to_string(const A (&v), int x1, int x2, C... coords) { int rnk = rank<A>::value; string tab(t_a_b_s, ' '); string res = ""; bool first = true; if (l_v_l_v_l == 0) res += n_l; res += tab + "["; x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v)); auto l = begin(v); advance(l, x1); auto r = l; advance(r, (x2 - x1) + (x2 < SIZE(v))); for (auto e = l; e != r; e = next(e)) { if (!first) { res += ", "; } first = false; l_v_l_v_l++; if (e != l) { if (rnk > 1) { res += n_l; t_a_b_s = l_v_l_v_l; }; } else { t_a_b_s = 0; } res += to_string(*e, coords...); l_v_l_v_l--; } res += "]"; if (l_v_l_v_l == 0) res += n_l; return res; } void dbgm() {;} template<typename Heads, typename... Tails> void dbgm(Heads H, Tails... T) { cout << to_string(H) << " | "; dbgm(T...); }
#define debug(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgm(__VA_ARGS__); cout << endl

void IO() {
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}
const int N = 105;
const int K = 1e5 + 5;
vector <int> ar(N);
int pref[N][K];
int dp[N][K];
int n, k;
inline int add(int a, int b) {
	a += b;
	if (a >= MOD)a -= MOD;
	return a;
}

inline int sub(int a, int b) {
	a -= b;
	if (a < 0)a += MOD;
	return a;
}
int32_t main() {
	//IO();
	fastio;
	cin.tie(nullptr);
	cout.tie(nullptr);
	cin >> n >> k;
	for (int i = 1; i <= n; i++) {
		cin >> ar[i];
	}
	for (int i = 0; i <= n; i++) {
		dp[i][0] = pref[i][0] = 1;
	}
	for (int i = 0; i <= k; i++) {
		dp[0][i] = pref[0][i] = 1;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= k; j++) {
			int L = (j - ar[i] - 1 >= 0) ? (pref[i - 1][j - ar[i] - 1]) : 0;
			int R = pref[i - 1][j];
			dp[i][j] = add(dp[i][j], sub(R, L));
			pref[i][j] = add(pref[i][j - 1], dp[i][j]);
		}
	}
	cout << dp[n][k] << endl;

	return 0;
}


Measured memory_bytes: 160000