///=======================///
/// coder: Andy - Tohrumi ///
///=======================///

#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define fastio ios_base::sync_with_stdio(); cin.tie(0); cout.tie(0);
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define rep(i, a, b) for(__typeof(b) i = a; i < b; i++)
#define Rep(i, a, b) for(__typeof(a) i = a; i > b; i--)

using namespace std;

typedef pair<ll, ll> pll;	typedef pair<int, int> ii;
typedef vector<pll> vll;	typedef vector<string> vs;		typedef vector<ii> vii;
typedef vector<int> vi; 	typedef vector<ll> vl;

///====code start here====///

const int mod = 1000000007;
const int N = 105, K = 100005;
ll dp[N][K], pre[N][K];

signed main() {
	fastio;
	ll n, k; cin >> n >> k;
	ll a[n]; rep(i, 0, n) cin >> a[i];
	
	rep(i, 0, a[0] + 1) dp[0][i] = 1;
	rep(i, 1, k + 2) pre[0][i] = pre[0][i - 1] + dp[0][i - 1];
	
	rep(i, 1, n) {
		rep(j, 0, k + 1) {
			dp[i][j] = (pre[i - 1][j + 1] - pre[i - 1][max(j - a[i], 0)]) % mod;
			pre[i][j + 1] = (pre[i][j] + dp[i][j]) % mod;
		}
	}
	
	return cout << dp[n - 1][k] << endl, 0;
}
