#include <iostream>
#include <cstring>

using namespace std;

typedef long long ll;

int n, k, a[105];
ll dp[100005];
const ll mod = (ll)1e9 + 7;

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

return 0;
}

