#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
// My bug list :
// integer overflow
// 0based, 1based forgotten
// index out of bound
// n, m, i, j typo
// some cases are missing

const int MAX_N = 510;

int n, c, p[MAX_N], q[MAX_N], a[MAX_N], b[MAX_N], ext[MAX_N];
int cnt[MAX_N];

int push(int x, int ind) {
    fill(cnt, cnt + n, 0);

    int ret = 0;
    while (x--) {
        int pos = -1, more = -1;
        for (int j = ind+1;j < n;++j) {
            if (cnt[j] == c) continue;
            if (chmax(more, ext[j]))
                pos = j;
        }
        if (pos == -1) break;
        ++ret;
        --ext[pos], ++cnt[pos];
    }
    return ret;
}
int solve() {
    int res = 0;
    for (int i = n-1;i >= 0;--i) {
        int x = min(p[i], a[i]), y = min(q[i], b[i]);
        res += x + y;
        p[i] -= x, a[i] -= x;
        q[i] -= y, b[i] -= y;
        ext[i] = a[i] + b[i];
        int v = push(p[i] + q[i], i);
        res += v;
    }
    return res;
}
int32_t main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    cin >> n >> c;
    for (int i = 0;i < n;++i) cin >> p[i];
    for (int i = 0;i < n;++i) cin >> q[i];
    for (int i = 0;i < n;++i) cin >> a[i];
    for (int i = 0;i < n;++i) cin >> b[i];

    cout << solve() << '\n';
}