#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define f(i, x, n) for (int i = x; i < (int)(n); ++i)
const int N = 1e5, M = 7 + 1e9;
int n, k, a[101], dp[101][N+1];
/*
	CHEAT MODE
*/
int main()
{
	cin >> n >> k;
	f(i, 1, n+1)
		cin >> a[i];
	dp[0][0] = 1;
	f(i, 1, n+1){
		vector<int> sum(k+1);
		f(w, 0, k+1)
			sum[w] = dp[i-1][w];
		f(w, 1, k+1)
			sum[w] = (sum[w] + sum[w-1])%M; // cumulative sum
		f(w, 0,k+1){ //sum[w-a[i] -> w ] 
			dp[i][w] = (sum[w] - (w-a[i]-1 < 0 ? 0 : sum[w-a[i]-1]) + M)%M;//rang
		}
	}
	cout << dp[n][k];
}