#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define fi first
#define se second

int n, k, a[107], dp[107][200007];
const int mod = 1e9 + 7;

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	cin >> n >> k;
	dp[0][k] = 1;
	for(int i = 1; i <= n; i++){
		cin >> a[i];
		int r = k, sum = 0;
		for(int j = k; j >= 0; j--){
			sum += dp[i - 1][j];
			if(sum >= mod) sum -= mod;
			sum = sum - dp[i - 1][j + a[i] + 1] + mod;
			sum %= mod;
			dp[i][j] = sum;
		}
	}
	cout << dp[n][0];
}
