#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr ll INF = ll(1e18);
constexpr int INF_IDX = int(1e9);
int n, k;
vector<int> a, b;
struct walker {
int i, j;
multiset<int> biggest_k, remainder;
ll sum_b = 0;
ll sum_biggest_k = 0;
walker(int x) { // interval from x to x
i = j = x;
add_elem(x);
}
ll value() {
if(j - i + 1 >= k)
return sum_biggest_k - sum_b;
else
return -INF;
}
void add_elem(int x) {
sum_b += b[x];
sum_biggest_k += a[x];
biggest_k.insert(a[x]);
if(biggest_k.size() > k) {
auto it = biggest_k.begin();
sum_biggest_k -= *it;
remainder.insert(*it);
biggest_k.erase(it);
}
}
void remove_elem(int x) {
sum_b -= b[x];
auto it = biggest_k.find(a[x]);
if(it != biggest_k.end()) {
sum_biggest_k -= a[x];
biggest_k.erase(it);
} else {
remainder.erase(remainder.find(a[x]));
}
if(biggest_k.size() < k && remainder.size() > 0) {
auto it2 = --remainder.end();
sum_biggest_k += *it2;
biggest_k.insert(*it2);
remainder.erase(it2);
}
}
void decrease_i() {
add_elem(--i);
}
void increase_i() {
remove_elem(i++);
}
void decrease_j() {
remove_elem(j--);
}
void increase_j() {
add_elem(++j);
}
void move(int ii, int jj) {
while(i > ii) decrease_i();
while(j < jj) increase_j();
while(i < ii) increase_i();
while(j > jj) decrease_j();
}
};
vector<ll> best_val_starting_at;
vector<int> opt_min;
void comp_opt_min(int l, int r, int opt_lo, int opt_hi, walker& walk) {
if(l > r) return;
int m = (l + r)/2;
ll best_val = -INF;
ll opt = INF_IDX;
for(int j = max(opt_lo, m); j <= opt_hi; ++j) {
walk.move(m, j);
if(walk.value() > best_val) {
best_val = walk.value();
opt = j;
}
}
opt_min[m] = opt;
best_val_starting_at[m] = best_val;
if(opt == INF_IDX) opt = opt_hi; // prevent weird edge cases
comp_opt_min(l, m-1, opt_lo, opt, walk);
comp_opt_min(m+1, r, opt, opt_hi, walk);
}
int main() {
cin >> n >> k;
a.resize(n);
b.resize(n);
for(auto &x : b) cin >> x;
for(auto &x : a) cin >> x;
opt_min.resize(n);
best_val_starting_at.resize(n);
{
walker walk(n/2);
comp_opt_min(0, n-1, 0, n-1, walk);
}
ll max_val = -INF;
for(int i = 0; i < n; ++i) {
max_val = max(max_val, best_val_starting_at[i]);
}
cout << max_val << endl;
}
