#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

#define ordered_set tree<pair<ll,int>, null_type,less<pair<ll,int>>, rb_tree_tag,tree_order_statistics_node_update>

using namespace std;
typedef long long ll;

const int MOD = 998244353;
const int mxN = 1e5 + 9;
const int mxM = 1e5 + 9;
const ll INF = 1e17 + 7;
const double eps = 1e-7;

ll segTree[8 * mxN], dp[mxN], preC[mxN], preA[mxN];
int A[mxN], C[mxN];

void updateTree (int v, int l, int r, int idx, ll val) {
    if (l == r) {
        segTree[v] = min (segTree[v], val);

        return;
    }

    int mid = (l + r) / 2;
    if (idx <= mid)
        updateTree (2 * v, l, mid, idx, val);
    else updateTree (2 * v + 1, mid + 1, r, idx, val);

    segTree[v] = min(segTree[2 * v], segTree[2 * v + 1]);
    return;
}

ll getMin (int v, int l, int r, int L, int R) {
    if (R < L)
        return INF;

    if (L <= l && r <= R)
        return segTree[v];

    if (l > R || r < L)
        return 0;

    int mid = (l + r) / 2;
    ll leftMin = getMin (2 * v, l, mid, L, R);
    ll rightMin = getMin (2 * v + 1, mid + 1, r, L, R);

    return min (leftMin, rightMin);
}

void buildTree (int v, int l, int r) {
    if (l == r) {
        segTree[v] = INF;

        return;
    }

    int mid = (l + r) / 2;
    buildTree (2 * v, l, mid);
    buildTree (2 * v + 1, mid + 1, r);

    segTree[v] = INF;
}

void solve () {
    int n, k;
    cin >> n >> k;

    for (int i = 1; i <= n; i++)
        cin >> A[i];

    for (int i = 1; i <= n; i++) {
        cin >> C[i];

        int sign = (C[i] == 2) ? 1 : -1;

        preA[i] = preA[i - 1] + A[i];
        preC[i] = preC[i - 1] + sign * C[i];
    }

    buildTree (1, 0, 2 * n);
    updateTree (1, 0, 2 * n, 0, 0);

    for (int r = 1; r <= n; r++) {
        preC[r] += n;
        int L = preC[r] - k, R = preC[r] + k;

        ll query = getMin (1, 0, 2 * n, max (L, 0), min (R, 2 * n));
        if (query == INF)
            dp[r] = -INF;
        else dp[r] = preA[r] - query;

        updateTree (1, 0, 2 * n, preC[r], preA[r]);
    }

    ll res = 0;
    for (int i = 1; i <= n; i++)
        res = max (res, dp[i]);

    cout << res << "\n";
    return ;
}

int main () {
    int t = 1;
    //cin >> t;

    //preCalc ();
    while (t--)
        solve ();

    return 0;
}

/*
 *
10 0
-1000 1
-100 2
-10 1
1 2
2 1
3 2
-100 1
2 2
5 2
-1000 2


 *
 */