#include <iostream>
#include <vector>
using namespace std;
const int maxn = 1005;
typedef long long ll;
const ll MOD = 1e9 + 7;

int main()
{
ios_base::sync_with_stdio(false);
int n, K;
cin >> n >> K;

vector<int> v(n);
for(int i = 0; i < n; i++) {
cin >> v[i];
}

vector<ll> dp(K + 1);
dp[0] = 1;
for(int at = 0; at < n; at++) {
for(int used_candies = K; used_candies >= 0; used_candies--) {
ll tmp = dp[used_candies];
int L = used_candies + 1;
int R = used_candies + min(v[at], K - used_candies);

for(int i = L; i <= R; i++) {
dp[i] += tmp;
dp[i] %= MOD;
}
// for(int candy = 1; candy <= min(v[at], K - used_candies); candy++) {
// dp[used_candies + candy] += tmp;
// dp[used_candies + candy] %= MOD;
// }
}
}

cout << dp[K] << endl;
return 0;
}