 #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cctype>
#include <cassert>
#include <climits>
#include <string>
#include <bitset>
#include <cfloat>
#include <unordered_set>
#include <iomanip>
using namespace std;
typedef long double ld;
typedef long long int ll;
typedef unsigned long long int ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
typedef vector<pair<int,int> > vpii;
typedef vector<vector<int> > vvi;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<ll> > vvll;
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define irep(it, stl) for(auto it = stl.begin(); it != stl.end(); it++)
#define drep(i,n) for(int i = (n) - 1; i >= 0; --i)
#define fin(ans) cout << (ans) << endl
#define mp(p,q) make_pair(p, q)
#define pb(n) push_back(n)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define Sort(a) sort(a.begin(), a.end())
#define Rort(a) sort(a.rbegin(), a.rend())
#define MATHPI acos(-1)
int dx8[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy8[8] = {0, 1, 0, -1, 1, 1, -1, -1};
int dx4[4] = {1, 0, -1, 0};
int dy4[4] = {0, 1, 0, -1};
template <class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;} return 0;}
template <class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;} return 0;}
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
struct io{io(){ios::sync_with_stdio(false);cin.tie(0);}};
const int INF = INT_MAX;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;
const double EPS = 1e-9;

//貰うDPを配るdpにして高速化、で式変形orBITor累積和によってまとめる,式変形はj-1を代入
int n,k;
vector<ll> a;
ll dp[110][100010];
ll mod = 1000000007;

ll modpow(ll a,ll n, ll mod){
    ll res = 1;
    while(n > 0){
        if(n & 1) res = res * a%mod;
        a = a*a%mod;
    n >>=1;
    }
    return res;
}
ll modMinus(ll val,ll m){
    ll res = val % m;
    if(res < 0) res += m;
        return res;
}
 void modAdd(ll &a,ll b){
a += b;
if(a >= MOD) a-= MOD;
}

int main(){
 cin >> n >> k;
 a.resize(n);
 for(int i = 0; i < n; ++i) cin >> a[i];
 for(int i = 0; i <= n; ++i) dp[i][0] = 1; //i人目までに0個配る方法は1通り

 for(int i = 1; i <= n; ++i){
   for(int j = 1; j <= k; ++j){
     dp[i][j] = modAdd(dp[i - 1][j],dp[i][j - 1]);
     if(j - a[i - 1] - 1 >= 0){
       dp[i][j] = modMinus(dp[i][j],dp[i - 1][j - a[i - 1] - 1]);
     }
   }
 }
 cout << dp[n][k] << endl;
 return 0;
}