
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

#define inf 1013161010
#define ninf -1013161010
#define mod 1000000007
#define ll long long
#define lf long double
#define in(x) scanf("%d",&x);
#define sz(x) ((int)x.size())
#define lld l64d
#define rep(i,n) for(i=0;i<n;i++)
#define rrep(i,n) for(i=n-1;i>=0;i--)
#define rep1(i,a,b) for(i=a;i<=b;i++)
#define rrep1(i,a,b) for(i=a;i>=b;i--)
#define stlfor(i,t) for(auto i =t.begin();i!=t.end();i++)
#define fr freopen("x.txt","r",stdin)
#define frc freopen("y.txt","w",stdout)
#define all(x) x.begin(),x.end()
#define set0(x) memset(x,0,sizeof(x))
#define dbg cout<<"yo "<<endl;
#define pset(n) fixed<<showpoint<<setprecision(n)

#define pii pair<int,int>
#define pll pair<ll,ll>
#define min_pq priority_queue<pll, vector<pll>, greater<pll> >
#define vpii vector<pair<int,int> >
#define vll vector<ll>
#define vpll vector<pair<ll,ll> >
#define si set<int>
#define mii map<int,int>
#define umii unordered_map<int,int>
#define vi vector<int>
#define pb push_back
#define ff first
#define ss second
#define mp make_pair
#define modulo %
#define moduloe %=

typedef tree<pii,null_type,less<pii>,rb_tree_tag,tree_order_statistics_node_update> OST;

ll toint(const string &s) { stringstream ss; ss << s; ll x; ss >> x; return x; }
ll add(ll a, ll b) {a+=b; while(a >= mod) a-= mod; while(a<0) a+= mod;}
ll mul(ll a, ll b) {return (a * 1LL *b % mod);}
string tostring ( ll number ){  stringstream ss; ss<< number; return ss.str();}

const lf pi = 2*acos(0);
const int nn = 500006;
const lf EPS = 0.000000001;

ll gcd(ll a,ll b){return (b==0)? a:gcd(b,a%b); }
void nope(int num = 0){ if(num==0) cout<<"NO"; else cout<<"-1"; exit(0); }


ll dp[103][100010];
ll sum[103][100010];
ll a[103];

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);
    ll i,j,n,tt;
    tt=1;
    //cin>>tt;
    while(tt--)
    {
        ll k;
        cin>>n>>k;
        rep1(i, 1, n)
            cin>>a[i];

        for(i=0;i<=n;i++)
            dp[i][0] = 1;

        for(i=0;i<=k;i++)
            sum[0][i] = 1;

        for(i=1;i<=n;i++)
        {
            for(j=1;j<=k;j++)
            {
                if(j - a[i] - 1 < 0)
                    dp[i][j] = sum[i-1][j];
                else
                    dp[i][j] = ( sum[i-1][j] - sum[i-1][j - a[i] - 1] + mod ) modulo mod;
            }

            sum[i][0] = dp[i][0];
            for(j=1; j<=k; j++)
            {
                sum[i][j] = sum[i][j-1] + dp[i][j];
                dp[i][j] moduloe mod;
            }
        }

        cout<<dp[n][k]<<endl;
    }
    return 0;
}

// read the question correctly (is y a vowel? what are the exact constraints?)
// look out for SPECIAL CASES (n=1?) and overflow (ll vs int?)
