#include <bits/stdc++.h>
#define l_ength size
using ll = long long;
const int mod = 1000000007;
const ll infll = (1ll<<60);
using namespace std;

ll dp[110][100010];
ll sum[100010];

int main(){
	int n, k; cin >> n >> k;
	vector<ll> a(n);
	for( auto &k : a ) cin >> k;
	dp[0][0] = 1;
	for( int i = 0; i <= k; ++i ){
		sum[i+1] = ( sum[i] + dp[0][i] ) % mod;
	}
	for( int i = 0; i < n; ++i ){
		for( int j = 0; j <= k; ++j ){
			dp[i+1][j] = ( sum[j+1] - sum[max(0, j-a[i])] + mod ) % mod;
		}
		for( int j = 0; j <= k; ++j ){
			sum[j+1] = ( sum[j] + dp[i+1][j] ) % mod;
		}
	}
	cout << dp[n][k] << endl;
}
