#include "bits/stdc++.h"
using namespace std;

int main() {
	long long N, K, A[100], MOD = 1000000007;
	static long long DP[110][100010] = {};
	DP[0][0] = 1;
	cin >> N >> K;
	for (int i = 0; i < N; i++) cin >> A[i];
	for (int i = 0; i < N; i++) {
		static long long SUM[100010] = {};
		for (int j = 0; j <= K; j++) {
			SUM[j + 1] = (SUM[j] + DP[i][j]) % MOD;
		}
		for (int j = 0; j <= K; j++) {
			DP[i + 1][j] = (SUM[j + 1] - SUM[max(0LL, j - A[i])] + MOD) % MOD;
		}
	}
	cout << DP[N][K] << endl;
}