#include<bits/stdc++.h>
                            using namespace std;

                            #define FOR(i,a,b) for(int i = (a); i < (b); i++)
                            #define rep(i,n) FOR(i,0,n)
                            #define RFOR(i,b,a) for(int i = (b) - 1; i>= (a); i--)
                            #define ITER(it, a) for(typeof(a.begin()) it = a.begin(); it != a.end(); it++)
                            #define FILL(a, value) memset(a, value, sizeof(a)

                            #define SZ(a) (int)a.size()
                            #define ALL(a) a.begin(), a.end()
                            #define PB push_back
                            #define MP make_pair
                            #define er erase
                            #define in insert
                            #define f first
//                            #define s second



                            typedef  long long LL;
                            typedef vector<int> VI;
                            typedef vector<LL > VL;
                            typedef vector<vector<int > > VVI;
                            typedef vector<vector<LL>> VVL;
                            typedef vector <vector<pair<int, int >> >VVPI;
                            typedef vector<vector<pair<LL, LL >> >VVPL;
                            typedef vector<pair<LL, LL >> PL;
                            typedef vector<PL> VPL;
                            typedef pair<int, int> PII;
                            typedef vector<PII> VPI;

                            const double PI = acos(-1.0);
                            const int INF = 1e9;
                            const LL LINF = (LL)1e18;

                            const double EPS = 1e-7;
                            const int MAS =  3 *1e5 + 10;
                            const int mod = 998244353;
                            const int MOD =1e9+7;
                            const int LOG= 19;
                            const int ar = 1e5 +100;
                            const int MAX = 1e6 + 1e2;
                            int dp[ar];
                            void add(int &a ,int b)
                            {
                                a+=b;
                                if(a >=MOD)a-=MOD;
                            }
                            void sub(int &a ,int b)
                            {
                                a-=b;
                                if(a < 0)a+=MOD;
                            }
                        int main() {
                            ios_base::sync_with_stdio(false);
                            cin.tie(NULL);
                            int n,k;
                            cin >> n >> k;
                            dp[0] = 1;
                            rep(i,n)
                            {
                                int x;
                                cin >> x;
                                VI fake(k + 1,0);
                                RFOR(sum,k + 1,0)
                                {
                                    int now = dp[sum];
                                    int l = sum + 1;
                                    int r =sum + min(x , k - sum);
                                    if(l <=r)
                                    {
                                        add(fake[l],now);
                                        if(r +1 <=k)
                                        {
                                            sub(fake[r + 1],now);
                                        }
                                    }
                                }
                                int magic = 0 ;
                                rep(i,k + 1)
                                {
                                    add(magic,fake[i]);
                                    add(dp[i],magic);
                                }
                            }
                            cout << dp[k];





                        }

















































Measured memory_bytes: 1024