#include <bits/stdc++.h>

#define ll long long

using namespace std;

int mod = (int)1e9 + 7;

int add(int a, int b) {
	return (a + b) % mod;
}

int dp[101][(int)1e5 + 1];
int n, k;

int main() {
	scanf("%d %d", &n, &k);
	dp[0][k] = 1;
	for (int i = 1, x; i <= n; i++) {
		scanf("%d", &x);
		int cur = 0;
		for (int j = k; j >= 0; j--) {
			cur = add(cur, dp[i - 1][j]);
			if (j + x + 1 <= k) {
				cur = add(cur, mod - dp[i - 1][j + x + 1]);
			} 
			dp[i][j] = cur;
		}
	}
	cout << dp[n][0];
}
