#include <iostream>
using namespace std;int a[105];int d[105][100005];
#define M 1000000007
#define r(i,a,b) for(int i=a;i<=b;i++)
int main(){ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);int n,k;cin>>n>>k;r(i,0,n-1){cin>>a[i];}r(i,0,a[0])d[0][i]=i+1;r(i,a[0]+1,k)d[0][i]=d[0][a[0]];r(i,1,n-1){d[i][0]=1;r(j,1,k){d[i][j]=d[i][j-1];d[i][j]+=(d[i-1][j]-(j-a[i]-1>=0?d[i-1][j-a[i]-1]:0))%M;d[i][j]%=M;}}cout<<(d[n-1][k]-d[n-1][k-1]+M)%M<<"\n";return 0;}