#include<bits/stdc++.h>
using namespace std;
using ll=long long;
ll mod=1e9+7;
int dp[101][100002];
vector<ll> v;
ll solve(int i,int j)
{
  if(dp[i][j]!=-1)
  return dp[i][j];
  if(i==0)
  return dp[i][j]=(j<=v[i]?1:0);
  if(j==0)
  return dp[i][j]=solve(i-1,j);
  ll ans=0;
  ans=(mod+solve(i,j-1)+solve(i-1,j)-((j-1-v[i]>=0)?solve(i-1,j-1-v[i]):0))%mod;
  return dp[i][j]=ans;
}
int main()
{
  memset(dp,-1,sizeof(dp));
  int n,k;
  cin>>n>>k;
  v.resize(n);
  for(ll& x:v)
  cin>>x;
  cout<<solve(n-1,k)<<endl;
  return 0;
}