#include <bits/stdc++.h>
#define rep(i,j,k) for(int i=(j);i<=(k);i++)
#define per(i,j,k) for(int i=(j);i>=(k);i--)
#define uint unsigned int
#define ll long long
#define ull unsigned long long
#define db double
#define ldb long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define mkp make_pair
#define eb emplace_back
#define SZ(S) (int)S.size()
//#define mod 998244353
//#define mod 1000000007
#define inf 0x3f3f3f3f
#define linf 0x3f3f3f3f3f3f3f3f
using namespace std;

template <class T>
void chkmax(T &x,T y){
	if(x < y) x = y;
}

template <class T>
void chkmin(T &x,T y){
	if(x > y) x = y;
}

inline int popcnt(int x){
	return __builtin_popcount(x);
}

inline int ctz(int x){
	return __builtin_ctz(x);
}


/*ll power(ll p,int k = mod - 2){
	ll ans = 1;
	while(k){
		if(k % 2 == 1) ans = ans * p % mod;
		p = p * p % mod;
		k /= 2;	
	}
	return ans;
}*/
int n,K;
int a[250005],b[250005];
ll ssum[250005];

set <pii> C,D;
ll cur;
void dbg(){
	printf("cur=%lld\n",cur);
	for(pii I:C) printf("(%d,%d) ",I.first,I.second);
	printf("\n");
	for(pii I:D) printf("(%d,%d) ",I.first,I.second);
	printf("\n");
}
void add(int p){
//	printf("add %d\n",p);
	if(SZ(C) < K){
		cur += b[p];
		C.insert(mkp(b[p],p));
		return;
	}else{
		auto it = prev(C.end());
		if(it->first < b[p]){
			cur -= it->first;
			cur += b[p];
			D.insert(mkp(it->first,it->second));
			C.erase(it);
			C.insert(mkp(b[p],p));
		}else{
			D.insert(mkp(b[p],p));
		}
	}
}

void del(int p){
	if(!p) return;
//	printf("del %d\n",p);
	auto it = D.find(mkp(b[p],p));
	if(it != D.end()){
		D.erase(it);
		return;
	}
	it = C.find(mkp(b[p],p));
	assert(it != C.end());
	cur -= b[p];
	C.erase(it);
	if(D.empty()) return;
	it = D.begin();
	cur += it->first;
	C.insert(mkp(it->first,it->second));
	D.erase(it);
}

int pl,pr;
ll eval(int l,int r){
	if(l > r) return -linf;
//	printf("eval [%d,%d]\n",l,r);
	while(l < pl) add(--pl);
	while(r > pr) add(++pr);
	while(pl < l) del(pl++);
	while(pr > r) del(pr--);
//	dbg();
	if(SZ(C) < K) return -linf;
	return cur - (ssum[r] - ssum[l - 1]); 
}

ll ans[250005];
int opt[250005];
void solve(int l,int r,int L,int R){
	if(l > r) return;
	int mid = (l + r) >> 1;
	ans[mid] = -linf;
	rep(i,L,R){
		if(eval(i,mid) >= ans[mid]){
			ans[mid] = eval(i,mid);
			opt[mid] = i;
		}
	}
	solve(l,mid - 1,L,opt[mid]);
	solve(mid + 1,r,opt[mid],R);
}

int main(){
//	freopen("test.in","r",stdin);
	scanf("%d%d",&n,&K);
	rep(i,1,n){
		scanf("%d",&a[i]);
		ssum[i] = ssum[i - 1] + a[i];
	}
	rep(i,1,n) scanf("%d",&b[i]);	
	pl = 1;pr = 0;
	solve(1,n,1,n);
	ll answer = -linf;
	rep(i,1,n) chkmax(answer,ans[i]);
	printf("%lld\n",answer);
	return 0;
}