#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define ff              first
#define ss              second
#define int             long long
#define pb              push_back
#define mp              make_pair
#define pii             pair<int,int>
#define vi              vector<int>
#define mii             map<int,int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             1000000007
#define inf             1e18
#define ps(x,y)         fixed<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
#define w(x)            int x; cin>>x; while(x--)
#define FIO             ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
mt19937                 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;

int32_t main()
{
	FIO;

	int n, k; cin >> n >> k;
	mk(a, n + 1, int);
	for (int i = 1; i <= n; i++)
		cin >> a[i];

	int dp[n + 1][k + 1];
	int pre[n + 1][k + 1];

	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= k; j++) {
			if (j == 0) {
				dp[i][j] = 1;
				pre[i][j] = 1;
			}
			if (i == 0) {
				dp[i][j] = 0;
				pre[i][j] = 1;
			}

			dp[i][j] += pre[i - 1][j] - pre[i - 1][max(0ll, j - a[i])] + 1;
			dp[i][j] %= mod;
		}
	}

	cout << dp[n][k] << endl;

	return 0;
}