#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long lu;
typedef long double ld;
typedef pair<ll,ll> pr;
typedef vector<ll> v;
typedef vector<vector<ll> > vv;
typedef vector<string>  vs;
typedef vector<pair<ll,ll>> vp;
#define in(x,n) for(ll i=0;i<n;i++)cin>>x[i]
#define mp make_pair
#define mt make_tuple
#define ld long double
#define f(i,n) for(ll i=0;i<n;i++)
#define ff(i,n) for(ll i=1;i<=n;i++)
#define  pb push_back
#define aa(s) s.begin(),s.end()
#define sz(x) (ll)x.size()
#define fi first
#define se second


#define mx(a) *(max_element(a.begin(),a.end()))
#define mn(a) *(min_element(a.begin(),a.end())

// #define p 908197
#define p  998244353
#define mod 1000000007


//#define mod  998244353
//#define mod 1000000000
#define  ti tuple
//#define mod 998000099999
#define sn struct node
#define MAXN   200001


const v dx = {1, -1, 0, 0};
const v dy = {0, 0, 1, -1};
const v dx1={0,1,-1,0,1,1,-1,-1};
const v dy1={1,0,0,-1,1,-1,1,-1};
const ld PI = 2 * acos(0.0);
ll cel(ll x1,ll y1){if((x1%y1)==0)return x1/y1;else return x1/y1+1;}
ll power(ll x, ll y)
{
    ll res = 1;	 // Initialize result
    x=x%mod;
    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = (res*x)%mod;

        // n must be even now
        y = y>>1; // y = y/2
        x = (x*x)%mod; // Change x to x^2
    }
    return res%mod;
}
ll power2(ll x, ll y)
{
    ll res = 1;	 // Initialize result
    x=x;
    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = (res*x);

        // n must be even now
        y = y>>1; // y = y/2
        x = (x*x); // Change x to x^2
    }
    return res;
}
ld power1(ld x, ll y)
{
    ld res = 1;	 // Initialize result
    //x=x%mod;
    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = (res*x);

        // n must be even now
        y = y>>1; // y = y/2
        x = (x*x); // Change x to x^2
    }
    return res;
}
void yes()
{
    cout<<"YES\n";
}
void no()
{
    cout<<"NO\n";
}



template<typename T> void print_queue(T& q) {
    while(!q.empty()) {
        std::cout << q.top() << " ";
        q.pop();
    }
    std::cout << '\n';
}



//ll dp[][w]={0};
/*vector<pair<ll,pair<ll,ll>>>v;ll len;
   ll dp[37][100002];
  ll solve(ll n,ll x,ll y,ll z,ll p)
  {
    if(n==len)
    {
        return 1;
    }
    if(dp[p][n]!=-1)
    {
        return dp[p][n];



    }
    ll ans=0;

      return dp[p][n]=ans;


  }
  */
/*
    vector<ll> merge(vector<ll> v1,vector<ll> v2)
    {
        vector<ll> x;
        ll i,j,k,l,m,n,o,p,q,r,s,t;
        m=v1.size();i=0;
        n=v2.size();j=0;
        while(i<m&&j<n)
        {
            if(v1[i]<v2[j])
            {
                x.push_back(v1[i]);
                i++;
            }
            else
            {
                x.push_back(v2[j]);
                j++;
            }
        }
        while(i<m)
        {
            x.push_back(v1[i]);
            i++;
        }
        while(j<n)
        {
            x.push_back(v2[j]);
            j++;
        }
        return x;
    }
    vector<ll>sa[1000000];
    ll a[1000000];
    void build(ll s,ll e,ll i)
    {
        if(s==e)
        {
            sa[i].push_back(a[s]);
            return;
        }
        ll m=(s+e)/2;
        build(s,m,2*i+1);
        build(m+1,e,2*i+2);
        sa[i]=merge(sa[2*i+1],sa[2*i+2]);
    }
    ll query(ll s,ll e,ll l,ll r,ll i,ll x1,ll x2)
    {
        if(e<l || r<s || s>e)
            return 0;
        if(s>=l && e<=r)
        {
            ll v1= upper_bound(sa[i].begin(),sa[i].end(),x1)-sa[i].begin();
           // ll v2= lower_bound(sa[i].begin(),sa[i].end(),x2-1)-sa[i].begin();
            return v1;
        }
        ll m=(s+e)/2;
        ll ls=query(s,m,l,r,2*i+1,x1,x2);
        ll rs=query(m+1,e,l,r,2*i+2,x1,x2);
        return ls+rs;
    }
*/







// Returns n^(-1) mod p
/*
ll modInverse(ll n)
{
    return power1(n, p-2);
}

// Returns nCr % p using Fermat's little
// theorem.
ll fac[500001];

ll nCrModPFermat(ll n, ll r)
{
    // Base case
    if (r==0)
        return 1;

    // Fill factorial array so that we
    // can find all factorial of r, n
    // and n-r


    return (fac[n]* modInverse(fac[r]) % p *
            modInverse(fac[n-r]) % p) % p;
}
 */
/*
vector<vector<pair<ll,ll>>>a(100003);
ll par[100003];ll size[100003];
ll find(ll x)
{
    while(par[x]!=x)
    {
        par[x]=par[par[x]];
        x=par[x];
    }
    return x;
}
void union1(ll x,ll y)
{
    ll xroot=find(x);
    ll yroot=find(y);
    if(xroot==yroot)
        return;
    if(size[xroot]>=size[yroot])
    {
        par[yroot]=xroot;
        size[xroot]+=size[yroot];
    } else
    {   par[xroot]=yroot;
        size[yroot]+=size[xroot];}
}
 */
void gv(v a,ll  n)
{
    f(i,n) {
        cin >> a[i];
//cout<<a[i]<<" ";
    }
//    cout<<"\n";
}
void out(v a,ll  n)
{
    f(i,n)
        cout<<a[i]<<" ";
    cout<<"\n";
}
void sor(v &a,v &b,ll n)
{
    vector<pair<ll,ll>>v;
    f(i,n)
    {
        // cout<<b[i]<<" "<<a[i]<<"\n";
        v.push_back(mp(a[i],b[i]));

    }
    sort(aa(v));
    f(i,n)
    {a[i]=v[i].first;b[i]=v[i].second;
    }
}


/*ll t;cin>>t;
f(wq,t) {
}
     */
/*
vector<vector<ll> > vec(row);
 vector<vector<ll> > vec( n , vector<ll> (m,0));
for(auto i:m2)
 */
//ll dp[101][101][27];


ll dp[101][100001];ll pre[101][100001];

int main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);

ll n,k;cin>>n>>k;
v a(n+1);
ff(i,n)
{
    cin>>a[i];
}
dp[0][0]=1;
f(i,k+1)
{
    pre[0][i]=1;

}
ff(i,n)
{
    f(j,k+1)
    {

        if(a[i]<j)
        dp[i][j]=(pre[i-1][j]-pre[i-1][j-a[i]-1]+mod)%mod;
        else
        {
            dp[i][j]=(pre[i-1][j])%mod;
        }

        if(j>0)
        pre[i][j]=(pre[i][j-1]+dp[i][j])%mod;
        else
        {
            pre[i][j]=dp[i][j];
        }
     //   cout<<dp[i][j]<<" ";
    }
   // cout<<"\n";
    //pre[i]
}
cout<<dp[n][k]%mod;
    return 0;
}



Measured memory_bytes: 158080