#include <bits/stdc++.h>

using namespace std;

long long dp[105][100005];
long long MOD = 1000000007;

int main(){
    int N, K;
    cin >> N >> K;
    if(!K){
        cout << 1 << endl;
        return 0;
    }
    for(int i = 0; i<=K; i++){
        dp[0][i] = 1;
    }
    for(int i= 1; i<=N; i++){
        int n;
        cin >> n;
        dp[i][0] = 1;
        for(int j =1; j<=K; j++){
            if(n >= j){
                dp[i][j] = dp[i-1][j];
            }
            else{
                dp[i][j] = (dp[i-1][j] - dp[i-1][j-n-1] + MOD)%MOD;
            }
            dp[i][j] = (dp[i][j] + dp[i][j-1])%MOD;
        }
    }
    cout << (dp[N][K]-dp[N][K-1] + MOD)%MOD;
}