#include<bits/stdc++.h>
using namespace std;
const int md = 1e9+7;
long long n, k, a, b[105][100005];

int main(){
    scanf("%lld%lld", &n, &k);
    fill(b[0],b[0]+k+1,1);
    for(int i = 0; i < n; i++){
        scanf("%lld", &a);
        b[i+1][0] = 1;
        for(int j = 1; j <= k; j++){
            b[i+1][j] = (b[i][j] - b[i][j-a-1<0 ? k+1 : j-a-1] + b[i+1][j-1] + md) % md;
        }
    }
    printf("%lld\n", (b[n][k] - b[n][k-1<0 ? k+1 : k-1] + md) % md);
}