#include 
#include 
#include 
#include 
using namespace std;
int n,k;
const int mod = 1e9 + 7;
int a[105];
int memo[100005];
void add_mod(int &a, int b) {
    a += b;
    if(a >= mod) {
        a -= mod;
    }
}
void subtract_mod(int &a, int b) {
    a -= b;
    if(a < 0) {
        a += mod;
    }
}
int main() {
    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    memset(memo,0,sizeof(memo));
    memo[0] = 1; // memo[i] - broj na nacini da stigneme so i candies
    for(int at = 0; at < n; at++) {
        vector pref_sum(k + 5, 0);
        for(int chocolates_left = k; chocolates_left >= 0; chocolates_left--) {
            int start = chocolates_left + 1;
            int end = chocolates_left + min(a[at], k - chocolates_left);
            if(start <= end) {
                add_mod(pref_sum[start], memo[chocolates_left]);
                subtract_mod(pref_sum[end + 1], memo[chocolates_left]);
            }
            
        }
        int sum = 0;
        for(int j = 0; j <= k; j++) {
            add_mod(sum, pref_sum[j]);
            add_mod(memo[j], sum);
        }
    }
    
        cout << memo[k] << endl;
    return 0;
}
// min(1, )