#pragma comment(linker, "/stack:247474112")
#pragma GCC optimize("Ofast")

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

#define sz(x) x.size()
#define clr(x) x.clear()
#define mem(x ,y) memset(x , y , sizeof x )
#define all(a ) a.begin() , a.end()
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define pii pair<int , int>
#define endl "\n"
#define fast()   ios_base :: sync_with_stdio(false ) ; cin.tie(0) ; cout.tie(0) ;
#define dbg(args...) do {   cerr << #args << ' ' ;  print(args); } while(0); cerr<< endl ;
#define dbgv(v ) rep(i, sz(v) )  cerr << v[i] << ' ' ;  cout << endl ;
#define dbga(x, n) rep(i , n ) cerr << x[i] << ' ' ;  cout << endl
#define forn(i,a,n ) for(int  i = a ; i <= n ; i++ )
#define rep(i ,n ) for(int i = 0 ; i < n ; i++ )
#define repi(i ,n ) for(int i = 1 ; i <= n ; i++ )
#define repit(i, c) for( __typeof((c).begin()) i = (c).begin(); i != (c).end();++i )

const long long  mod = 1e9+7 ;
const int inf = 1e9  ;
const long long  lnf = 1e18 ;
 
int setbit(int n, int pos  ) { return n = n|(1<< pos) ; }
int resetbit(int n,int pos ) {  return n =  n & ~(1<<pos ); }
bool checkbit(int n,int pos ) { return (bool ) (n& (1<<pos))  ; }

template< typename T > void print(const T& v) {    cerr << v << ' ' ;}
template< typename T > T modMul(T x, T y ) { x %= mod ; y %= mod ; return (x*y)%mod  ;  }
template< typename T > T modAdd(T x, T y  ) { x %= mod ; y %= mod ; return (x+y)%mod ;  }
template< typename T > T modPow(T x, T k ) { if(k == 0 ) return 1; if(k&1  ) { return ( (x%mod)*modPow(x,k-1, mod )%mod )%mod ; } else { T ret = modPow(x,k/2 , mod ) ; ret %= mod ; return (ret*ret )%mod; } }
template< typename T1, typename... T2 > void print( const T1& first, const T2&... rest ){ print(first); print(rest...) ;}
template< typename T > T ext_gcd(T num1 , T num2, T &X , T &Y ) { T r2,r1, q2, q1 , x2, x1, y2 ,y1 , x,  y, r   ; x2 = 1; y2 = 0;  x1 = 0; y1 = 1; for( r2 =num1 ,r1 = num2 ;r1 != 0 ; y2 = y1, y1 = y,x2 = x1 ,x1 = x ,r2 = r1, r1 = r) {q1 = r2/r1; x = x2 - q1*x1; y = y2 - q1*y1; r = r2%r1 ; } X = x2 ; Y = y2 ; return r2 ;  } 

template<typename T >
T modInv( T x , T m ) {  
    return modPow(x,m-2 , m) ; 
    long long ret, t ;
    ext_gcd( x, m ,ret ,t  ) ;
    ret %= m ;
    if(ret<0) ret += m  ;
    return ret;
}

typedef long long ll  ;
typedef unsigned long long  ull ;
typedef vector<int> vi  ;

//int dx[] = {0 , 0 ,+1, -1 } ;
//int dy[] = {-1, +1,0 , 0 };
 
///////////////////////////// all functions below this line  ///////////////////////////////////////////////////

const int M = 200002 ;  
//const ll N = 1e1 ;
//const int N =10;

struct mc{    
    ll x,y ,z  ;
    mc(){} 
    mc(ll a, ll b ,ll c ) { x=a; y=b ;    z=c; } 
    bool operator<(mc a ) const {
        return x<a.x; 
    }
} ; 

ll dp[101][100001] ,a[M+2],candy, n  ;
int func(int id, int  k ) {
    if(id<1 ) {
        return (k==0) ;

    }
    int ans =0 ; 
    
    rep(i,a[id ]+1 ) ans += func(id-1, k-i) ;

    return ans ; 
}

ll calc(int id,int j) {
    int have  = min(a[id+1], candy ) ;
    if(j-have <= 0 ) return dp[id][j ] ;
    return dp[id][j]-dp[id][j-have-1] ;





}

void solve() {  
    dp[0][0] =1LL; 
    cin >> n >> candy ;
    repi(i ,n ) cin >> a[i] ;
    repi(i,candy  ) dp[0][i] += dp[0][i-1] ;

    repi(i, n ) {  
       // cout << i <<  "-> " ;
        rep(j , candy+1  ) {
          dp[i][j] = modAdd(dp[i][j] , calc(i-1,j ) )  ;
        


        } 
        //break;
        if(i!=n )repi(j , candy ) dp[i][j ]+=dp[i][j-1] ;
        //cout << endl;
    }
    cout << dp[n][candy] << endl;
}

int main() {
       //  freopen("in.txt", "r", stdin  );
    // freopen( "out.txt", "w",stdout );     
    fast(); 

    int t=1; 
    // si(t) ;
    while( t-- ){
        
          

        solve() ;


    }




    return 0 ;




}


Measured memory_bytes: 79232