#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
typedef pair<double,double> pdd;
#define MEM(a, b) memset(a, (b), sizeof(a))
#define SZ(i) ll(i.size())
#define FOR(i, j, k, in) for (ll i=j ; i<k ; i+=in)
#define RFOR(i, j, k, in) for (ll i=j ; i>=k ; i-=in)
#define REP(i, j) FOR(i, 0, j, 1)
#define REP1(i,j) FOR(i, 1, j+1, 1)
#define RREP(i, j) RFOR(i, j, 0, 1)
#define ALL(_a) _a.begin(),_a.end()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define X first
#define Y second
#ifdef tmd
#define debug(...) do{\
    fprintf(stderr,"%s - %d (%s) = ",__PRETTY_FUNCTION__,__LINE__,#__VA_ARGS__);\
    _do(__VA_ARGS__);\
}while(0)
template<typename T>void _do(T &&_x){cerr<<_x<<endl;}
template<typename T,typename ...S> void _do(T &&_x,S &&..._t){cerr<<_x<<" ,";_do(_t...);}
template<typename _a,typename _b> ostream& operator << (ostream &_s,const pair<_a,_b> &_p){return _s<<"("<<_p.X<<","<<_p.Y<<")";}
template<typename It> ostream& _OUTC(ostream &_s,It _ita,It _itb)
{
    _s<<"{";
    for(It _it=_ita;_it!=_itb;_it++)
    {
        _s<<(_it==_ita?"":",")<<*_it;
    }
    _s<<"}";
    return _s;
}
template<typename _a> ostream &operator << (ostream &_s,vector<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s,set<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a,typename _b> ostream &operator << (ostream &_s,map<_a,_b> &_c){return _OUTC(_s,ALL(_c));}
template<typename _t> void pary(_t _a,_t _b){_OUTC(cerr,_a,_b);cerr<<endl;}
#define IOS()
#else
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0)
#endif

template<class T> inline bool cmax(T &a, const T &b) { return b > a ? a = b, true : false; }
template<class T> inline bool cmin(T &a, const T &b) { return b < a ? a = b, true : false; }
template<class T> using MaxHeap = priority_queue<T>;
template<class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;

const ll MOD=1000000007;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll MAXN=1e5+5;
const ll MAXLG=__lg(MAXN)+2;

ll n,k;
ll dp[104][MAXN],a[MAXN];

/********** Good Luck :) **********/
int main()
{
    IOS();
    cin >> n >> k;
    REP (i,n) {
        cin >> a[i];
    }

    REP (i,min(a[0],k)+1) {
        dp[0][i] = 1;
    }

    REP1 (i,n-1) {
        deque<pii> dq;
        ll sum = 0;
        REP (j,k+1) {
            while (dq.size() && j- dq.front().X >= a[i]){
                sum -= dq.front().Y;
                if (sum < 0) {
                    sum += MOD;
                }
                dq.pop_front();
            } 
            dq.emplace_back(i,dp[i-1][j]);
            sum = (sum + dp[i-1][j]) % MOD;

            dp[i][j] = sum;
        }
    }
    // for (int i=0;i<n;i++) {
    //     pary(dp[i],dp[i]+k+1);
    // }
    cout << dp[n-1][k] << endl;
    return 0;
}
