#include <bits/stdc++.h>

using namespace std;
typedef long long LL;

int a[110];
int dp[2][100010];
int MOD=1000000007;

int main() {
    int n, k;
    cin>>n>>k;
    for (int i=0;i<n;i++) cin>>a[i];
    memset(dp,0,sizeof(dp));
    dp[0][0]=dp[1][0]=1;
    for (int i=0;i<n;i++) {
        int sum=1;
        for (int j=1;j<=k;j++) {
            sum+=dp[i%2][j];
            if (j>a[i]) sum-=dp[i%2][j-a[i]-1];
            sum=(sum%MOD+MOD)%MOD;
            dp[(i+1)%2][j]=sum;
        }
    }
    cout<<dp[n%2][k]<<endl;
}