#include <bits/stdc++.h>
#define  pb push_back
#define nl "\n"
#define fastScan ios_base::sync_with_stdio(0); cin.tie(NULL);
#define int long long int
using namespace std;
int s[123456];
int dp[123][123456];
signed main()
{
	fastScan;
	int n,k;cin>>n>>k;
	for(int i=1;i<=n;i++)
		cin>>s[i];
	dp[0][0]=1;
	int mod=(int)(1e9+7);
	for(int i=1;i<=n;i++)
	{
		int pre=0;
		for(int j=0;j<=k;j++)
		{
			pre+=dp[i-1][j];
			if(j-s[i]-1>=0)
				pre-=dp[i-1][j-s[i]-1];
			pre=(pre%mod+mod)%mod;
			dp[i][j]=pre;
		}
	}
	cout<<dp[n][k]<<nl;
}
