wifi

//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 1000005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;

int n, k, a[N], val[N], f[N];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> n >> k;
    for(int i=1; i<=n; i++) cin >> a[i];
    for(int i=1; i<=n; i++) cin >> val[i];
}

int bs(int l, int r, int val)
{
    int mid = (l + r)/2;
    if (l == r) return l;
    if (r - l == 1)
    {
        if (a[r] <= val) return r;
        return l;
    }
    if (a[mid] <= val) return bs(mid,r,val);
    return bs(l,mid,val);
}

void proc()
{
    a[0] = -9999;
    f[0] = 0;
    for(int i=1; i<=n; i++)
    {
        f[i] = val[i];
        int j = bs(0,i-1,a[i]-k);
        f[i] += f[j];
    }
    cout << f[n];
}

signed main()
{
    readfile();
    proc();
    return 0;
}