/* AUTHOR: TUAN ANH - BUI */
// ~~ icebear ~~
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
template<class X, class Y>
bool minimize(X &x, const Y &y) {
if (x > y) return x = y, true;
return false;
}
template<class X, class Y>
bool maximize(X &x, const Y &y) {
if (x < y) return x = y, true;
return false;
}
#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "gen"
/*END OF TEMPLATE. ICEBEAR AND THE CAT WILL WIN TST26 */
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 27092008;
const ll INF = (ll)1e18 + 27092008;
const int N = 250000 + 5;
int n, k, c[N], s[N];
ll pref[N];
int opt[N];
struct PersistentSegmentTree {
struct Node {
int l, r;
int cnt;
ll sum;
Node(int _cnt = 0, ll _sum = 0): l(0), r(0), cnt(_cnt), sum(_sum) {}
} node[N * 27];
int version[N], curVer = 0, treeNode = 0;
void combine(int id) {
node[id].cnt = node[node[id].l].cnt + node[node[id].r].cnt;
node[id].sum = node[node[id].l].sum + node[node[id].r].sum;
}
int build(int l, int r) {
if (l == r) return ++treeNode;
int mid = (l + r) >> 1;
int id = ++treeNode;
node[id].l = build(l, mid);
node[id].r = build(mid + 1, r);
combine(id);
return id;
}
int update(int old, int l, int r, int pos, int val) {
if (l == r) {
node[++treeNode] = Node(node[old].cnt + 1, node[old].sum + val);
return treeNode;
}
int mid = (l + r) >> 1;
int id = ++treeNode;
if (pos <= mid) {
node[id].l = update(node[old].l, l, mid, pos, val);
node[id].r = node[old].r;
} else {
node[id].l = node[old].l;
node[id].r = update(node[old].r, mid + 1, r, pos, val);
}
combine(id);
return id;
}
ll sumKth(int L, int R, int K, int l, int r) {
if (K >= node[R].cnt - node[L].cnt) return node[R].sum - node[L].sum;
if (l == r) return 0;
int mid = (l + r) >> 1;
if (node[node[R].r].cnt - node[node[L].r].cnt <= K)
return node[node[R].r].sum - node[node[L].r].sum + sumKth(node[L].l, node[R].l, K - node[node[R].r].cnt + node[node[L].r].cnt, l, mid);
else
return sumKth(node[L].r, node[R].r, K, mid + 1, r);
}
void build() {
version[0] = build(1, n);
}
void update(int pos, int val) {
version[curVer + 1] = update(version[curVer], 1, n, pos, val);
curVer++;
}
ll sumKth(int l, int r, int k) {
return sumKth(version[l - 1], version[r], k, 1, n);
}
} PerIT;
void DnC(int l, int r, int optL, int optR) {
if (l > r) return;
int mid = (l + r) >> 1;
ll best = -INF;
FOR(i, max(optL, mid + k - 1), optR) {
if (maximize(best, PerIT.sumKth(mid, i, k) - pref[i] + pref[mid - 1]))
opt[mid] = i;
}
DnC(l, mid - 1, optL, opt[mid]);
DnC(mid + 1, r, opt[mid], optR);
}
void init(void) {
cin >> n >> k;
FOR(i, 1, n) cin >> c[i], pref[i] = pref[i - 1] + c[i];
FOR(i, 1, n) cin >> s[i];
vector<ii> compress;
FOR(i, 1, n) compress.pb(mp(s[i], i));
sort(all(compress));
vector<int> ord(n + 5, 0);
FOR(i, 0, n - 1) ord[compress[i].se] = i + 1;
PerIT.build();
FOR(i, 1, n) PerIT.update(ord[i], s[i]);
}
void process(void) {
DnC(1, n, 1, n);
ll best = -INF;
FOR(i, 1, n - k + 1) maximize(best, PerIT.sumKth(i, opt[i], k) - pref[opt[i]] + pref[i - 1]);
cout << best << '\n';
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int tc = 1;
// cin >> tc;
while(tc--) {
init();
process();
}
return 0;
}
