//Dedicated to my love, ivaziva
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(a) ((int)a.size())
const int N=3e5+5;
ll n, m;
ll a[N], b[N];
int main () {
ios::sync_with_stdio(false), cin.tie(0);
cin >> n >> m;
for (ll i=1; i<=n; i++)
cin >> a[i];
for (ll i=1; i<=n; i++)
cin >> b[i];
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
for (ll i=1; i<=n; i++) {
pq.push(make_pair(0ll, i));
}
for (ll j=1; j<=m; j++) {
for (ll i=1; i<=n; i++) {
auto x=pq.top();
pq.pop();
if (x.second==i)
x.first+=max(a[i], b[i]);
else
x.first+=b[x.second];
pq.push(x);
}
}
cout << pq.top().first << '\n';
}
