#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ld,ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a,b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a,b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
/*
*/
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
void solve(int test_case)
{
ll n,k; cin >> n >> k;
vector<ll> a(n+5), b(n+5);
rep1(i,n) cin >> a[i];
rep1(i,n) cin >> b[i];
vector<pll> dp(n+5,{-1,-1});
auto go = [&](ll i, ld lambda, auto &&go) -> pll{
if(i > n) return {0,0};
if(dp[i].ss != -1) return dp[i];
auto p1 = go(i+1,lambda,go), p2 = go(i+1,lambda,go);
p1.ff += -a[i];
p2.ff += -a[i]+b[i]-lambda;
auto px = p1;
if(p2.ff >= p1.ff){
px = p2;
px.ss++;
}
return dp[i] = px;
};
auto get = [&](ld lambda){
fill(all(dp),pll{-1,-1});
pll ans = {0,0};
rep1(i,n){
amax(ans,go(i,lambda,go));
}
return ans;
};
ld lo = -inf1, hi = inf1;
ld lambda = inf1+1;
rep(iter,100){
ld mid = (lo+hi)/2;
auto [cost,cnt] = get(mid);
if(cnt <= k){
amin(lambda,mid);
hi = mid;
}
else{
lo = mid;
}
}
auto [cost,cnt] = get(lambda);
ll ans = round(cost+lambda*cnt);
cout << ans << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
