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

#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

//namespaces
using namespace __gnu_pbds; 
using namespace std;

//MACROS
#define ld long double
#define pb push_back
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll long long
#define ull unsigned long long 
#define For(i,s,e) for (int i=(s); i<(e); i++)
#define Fod(i,s,e) for (int i=(s); i>=(e); i--)
#define pii pair<ll,ll>
#define f first
#define s second
#define endl "\n"
#define all(container) container.begin(), container.end()
#define mp make_pair

//debug
#define TRACE
#ifndef ONLINE_JUDGE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
    cerr << name << " : " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
    const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...)
#endif

//Templates
template <typename T>
using ordered_set =tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <class T> ostream& operator << (ostream &os, const vector<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T> ostream& operator << (ostream &os, const set<T> &v) { for (T i : v) os << i << ' '; return os; }
template <class T, class S> ostream& operator << (ostream &os, const pair<T, S> &v) { os << v.first << ' ' << v.second; return os; }
template <class T, class S> ostream& operator << (ostream &os, const unordered_map<T, S> &v) { for (auto i : v) os << '(' << i.first << "=>" << i.second << ')' << ' '; return os; }

//globals
ll const prime1 = 304933;
ll const prime2 = 15486277;
ll const mod = 1e9+7;
ll const inf = 1e18;
ll const size_1d = 1e5 + 7;
ll const size_2d = 1e3 + 7;

//functions
ll power(ll x, ll y, ll mod = 2e18){ ll ans = 1;x %= mod;while(y){if(y&1)ans = (x * ans) % mod;x = (x * x) % mod;y >>= 1;}return ans;}
ll modInverse(ll a, ll m){ll m0 = m;ll y = 0, x = 1;if (m == 1) return 0;while (a > 1){ ll q = a / m;ll t = m;m = a % m,a = t;t = y;y = x - q * y;x = t;}if(x < 0) x += m0;return x;} 
ll gcdext(ll a,ll b,ll *x = 0, ll *y = 0){if(a == 0){*x = 0;*y = 1;return b;}ll x1,y1;ll gcd1 = gcdext(b%a,a,&x1,&y1);*x = y1 - (b/a)*x1;*y = x1;return gcd1;}
int randomize(){return (rand()%10000);} 

// CODE STARTS HERE
ll dp[101][size_1d];

int main(){
    IOS

    int n,k;cin >> n >> k;
    std::vector<int> v(n);
    for (int i = 0; i < n; ++i)
    {
        cin >> v[i];
    }
    memset(dp,0,sizeof(dp));
    dp[0][0] = 1;
    For(i,1,n + 1){
        ll sum[k + 2] = {0};
        sum[0] = dp[i-1][0];
        For(j,1,k + 1){;
            sum[j] = (sum[j-1] + dp[i-1][j])%mod;
        }
        For(j,0,k + 1){
            // trace(sum[j]);
            ll kt = sum[j];
            ll un = j - v[i-1] - 1;
            if(un + 1 > 0){
                kt = (kt - sum[un] + mod)%mod;
            }
            // trace(kt);
            // trace(dp[i][j]);
            dp[i][j] = kt;
        }
    }
    cout << dp[n][k] << endl;

    return 0;
}

Measured memory_bytes: 80000