#include<bits/stdc++.h> 
using namespace std;
#define MOD 1000000007
using ll = long long ;
 
ll arr[105],dp[105][100005];
int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	ll i,j,n,k;
	cin>>n>>k;
	for(i=1;i<=n;i++) cin>>arr[i];
	dp[0][0]=1; 
	for(i=1;i<=k;i++) dp[0][i]=0; 
	for(i=1;i<=n;i++){
		for(j=1;j<=k;j++)
			dp[i-1][j]=(dp[i-1][j]+dp[i-1][j-1])%MOD;
			
		for(j=0;j<=k;j++){
			ll mn=j-arr[i]-1;
			dp[i][j]=dp[i-1][j];
			if(mn>=0) dp[i][j]=(dp[i][j]-dp[i-1][mn]+MOD)%MOD;
		}
	}
	cout<<dp[n][k]<<endl;
	return 0;
}