#include <bits/stdc++.h>
#ifdef LOCAL
#include "./debug.cpp"
#else
#define debug(...)
#define print_line
#endif
using namespace std;
using ll = long long;

template <typename T>
struct segment_tree {
    using F = function<T(T, T)>;
    segment_tree(int n, F f, T e) {
        this->n = 1;
        while (this->n < n) {
            this->n *= 2;
        }
        this->size = n;
        this->f = f;
        this->e = e;
        dat = vector<T>(this->n * 2 - 1, e);
    }
    void build(const vector<T> &a) {
        for (int i = 0; i < (int)a.size(); i++) {
            dat[i + n - 1] = a[i];
        }
        for (int i = n - 2; i >= 0; i--) {
            dat[i] = f(dat[i * 2 + 1], dat[i * 2 + 2]);
        }
    }
    void set(int i, T x) {
        i += n - 1;
        dat[i] = x;
        while (i > 0) {
            i = (i - 1) / 2;
            dat[i] = f(dat[i * 2 + 1], dat[i * 2 + 2]);
        }
    }
    T query(int l, int r) {
        return query(l, r, 0, 0, n);
    }
    T operator[](int i) {
        return dat[n - 1 + i];
    }
    int size;

private:
    int n;
    vector<T> dat;
    F f;
    T e;
    T query(int left, int right, int i, int l, int r) {
        if (r <= left || right <= l) {
            return e;
        } else if (left <= l && r <= right) {
            return dat[i];
        } else {
            int mid = (l + r) / 2;
            return f(query(left, right, i * 2 + 1, l, mid), query(left, right, i * 2 + 2, mid, r));
        }
    }
};

template <typename T>
segment_tree<T> range_min_query(int n, T e = numeric_limits<T>::max()) {
    auto f = [](T a, T b) {
        return min(a, b);
    };
    return segment_tree<T>(n, f, e);
}

template <typename T>
segment_tree<T> range_max_query(int n, T e = numeric_limits<T>::min()) {
    auto f = [](T a, T b) {
        return max(a, b);
    };
    return segment_tree<T>(n, f, e);
}

template <typename T>
segment_tree<T> range_sum_query(int n, T e = 0) {
    auto f = [](T a, T b) {
        return a + b;
    };
    return segment_tree<T>(n, f, e);
}

struct S {
    ll val, len, base;
};

S f(S a, S b) {
    S ret;
    ret.val = a.val + a.len * b.base + b.val;
    ret.len = a.len + b.len;
    ret.base = a.base + b.base;
    return ret;
}

S fe = S{0, 0, 0};

int main() {
    int N;
    ll H;
    cin >> N >> H;
    vector<int> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }
    vector<int> B(N);
    for (int i = 0; i < N; i++) {
        cin >> B[i];
    }

    segment_tree<S> seg(N, f, fe);
    for (int i = 0; i < N; i++) {
        seg.set(i, S{B[i], 1, B[i]});
    }

    vector<ll> pref(N + 1);
    for (int i = 0; i < N; i++) {
        pref[i + 1] = pref[i] + A[i];
    }

    ll ans = 0;
    for (int i = 0; i < N; i++) {
        if (B[i] > H) {
            continue;
        }
        int lo = i, hi = N;
        while (hi - lo > 1) {
            int mid = (lo + hi) / 2;
            ll sumb = seg.query(i, mid + 1).val;
            if (sumb <= H) {
                lo = mid;
            } else {
                hi = mid;
            }
        }

        ans = max(ans, pref[lo + 1] - pref[i]);
    }

    cout << ans << endl;
}