#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;
}