AC

#include <iostream>
#include <vector>

using namespace std;

const int MOD = 1000007;

int main() {

int n, m;
cin >> n >> m;
vector<int> a(n + 1);
for (int i = 1; i <= n; ++i) {
    cin >> a[i];
}
vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
dp[0][0] = 1;

for (int i = 1; i <= n; ++i) {
    for (int j = 0; j <= m; ++j) {
        for (int k = 0; k <= a[i] && k <= j; ++k) {
            dp[i][j] = (dp[i][j] + dp[i - 1][j - k]) % MOD;
        }
    }
}

cout << dp[n][m] << endl;
return 0;

}