#include"bits/stdc++.h"
using namespace std;
int f[101][100001];
int n,m;
int a[101];
int s[100001];
int main()
{
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	f[0][0]=1;
	for(int i=1;i<=n;i++)
	{
		f[i][0]=1;
		s[0]=1;
		for(int j=1;j<=m;j++)
			s[j]=((long long)s[j-1]+f[i-1][j])%1000000007;
		for(int j=1;j<=m;j++)
		{
			if(a[i]>=j)
				f[i][j]=s[j];
			else
				f[i][j]=((long long)s[j]-s[j-a[i]-1]+1000000007)%1000000007;
		}
	}
	printf("%d",f[n][m]);
}