#include <cstdio>
#include <queue>
#include <algorithm>
using namespace std;
typedef pair<int,int> pi;
typedef long long lint;
int x[150005], y[150005], n;
int h;
long long res;
struct rmq{
pi tree[530000];
int lim;
void init(int n, int *a){
for(lim = 1; lim <= n; lim <<= 1);
for(int i=0; i<n; i++){
tree[i+lim] = pi(a[i],i);
}
for(int i=lim-1; i; i--){
tree[i] = min(tree[2*i],tree[2*i+1]);
}
}
int q(int s, int e){
s += lim;
e += lim;
pi t(1e9,1e9);
while(s < e){
if(s%2 == 1) t = min(t,tree[s++]);
if(e%2 == 0) t = min(t,tree[e--]);
s >>= 1;
e >>= 1;
}
if(s == e) t = min(t,tree[s]);
return t.second;
}
}rmq;
priority_queue<lint> pq;
lint f(int s, int e){
if(s >= e) return 0;
int pos = rmq.q(s,e-1);
int ph = h;
h = y[pos];
lint f1 = f(s, pos);
lint f2 = f(pos+1, e);
pq.push(min(f1, f2));
h = ph;
return max(f1, f2) + 1ll * (x[e] - x[s]) * (y[pos] - ph);
}
int main(){
scanf("%d",&n);
n/=2;
for (int i=0; i<n; i++) {
scanf("%*d %*d %d %d",&x[i],&y[i]);
}
rmq.init(n,y);
pq.push(f(0, n-1));
int k;
scanf("%d",&k);
lint ret = 0;
for(int i=0; i<k && !pq.empty(); i++){
ret += pq.top();
pq.pop();
}
printf("%lld",ret);
}
