#include<bits/stdc++.h>
#define ll long long
#define mod 1000000007
using namespace std;

ll n,k;
vector<ll> v(101);

ll solve(){
	ll dp[n+2][k+2];
	
	for(ll i=0;i<=k;i++){
	  dp[1][i]=(i > v[1])?0:1;
	}
	
	for(ll i=2;i<=n;i++){
		for(ll j=0;j<=k;j++){
			if(j==0)
				dp[i][j]=dp[i-1][j]%mod;
			else{
				dp[i][j]=(mod + dp[i][j-1]+dp[i-1][j]-((j-v[i]-1>=0)?dp[i-1][j-v[i]-1]:0))%mod;
			}
		}
	}
	return dp[n][k]%mod;
}

int main(){
	cin>>n>>k;
	for(ll i=1;i<=n;i++){
		cin>>v[i];
	}
	cout<<solve()<<endl;
}