#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000
#define int long long
int dp[110][100010];

signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N, K; cin >> N >> K;
    int a[110];
    rep(i, N) cin >> a[i];
    dp[0][0] = 1;
    rep(i, N) {
        rep(j, K + 1) {
            dp[i + 1][j] = dp[i + 1][j - 1] + dp[i][j];
            if (j - 1 - a[i] >= 0) {
                dp[i + 1][j] -= dp[i][j - 1 - a[i]];
            }
            dp[i + 1][j] = (dp[i + 1] + mod) % mod;
        }
    }
    /*
    rep(i, N + 1) {
        rep(j, K + 1) {
            cout << dp[i][j] << " ";
        }
        cout << endl;
    }
    */
    cout << dp[N][K] << endl;

    return 0;
}
