#include <algorithm>
#include <iostream>
using namespace std;

using ll = long long;

constexpr ll MOD = 1000000007;

int N, K, a[300];
ll dp[300][300*(300-1)/2+1];

int main() {
    cin.tie(0); ios::sync_with_stdio(false);
    cin >> N >> K;
    for (int j = 0; j < N; ++j) cin >> a[j];
    for (int j = 0; j < N; ++j) fill(dp[j], dp[j]+N*(N-1)/2, 0);
    dp[0][0] = 1;
    for (int j = 1; j < N; ++j) {
        for (int k = 0; k <= K; ++k) {
            dp[j][k] = dp[j-1][k];
            if (k > 0) dp[j][k] = (dp[j][k] + dp[j][k-1]) % MOD;
            if (k > j) dp[j][k] = (dp[j][k] - dp[j-1][k-j-1] + MOD) % MOD;
        }
    }
    
    ll ans = 0;
    for (int j = 0; j <= K; ++j) {
        ans = (ans + dp[N-1][j]) % MOD;
    }
    cout << ans << endl;

    return 0;
}