灵异事件

#include <iostream>
#include <cmath>
using namespace std;

const int N = 10;
const double PI = 3.1415926535;
struct node{
	double x, y;
}a[N];
bool vis[N];
double x1, y1, x2, y2;
double ans;
double r[N];
int n;

double calc(int i){ // 求半径 
	//到边界 
	double s1 = min(abs(a[i].x - x1), abs(a[i].x - x2));
	double s2 = min(abs(a[i].y - y1), abs(a[i].y - y2));
	double fans = min(s1, s2);
	//到油滴 
	for(int j = 1; j <= n; j++){
		if(i != j && vis[j]){
			double finalans=sqrt((a[i].x-a[j].x)*(a[i].x-a[j].x)+(a[i].y-a[j].y)*(a[i].y-a[j].y));
			fans = min(fans, max(finalans - r[j], 0.0));
		}
	}
	return fans;
}

void dfs(int dep, double sum){
	if(dep > n){
		ans = max(ans, sum);
		return ;
	}
	for(int i = 1; i <= n; i++){
		if(!vis[i]){
			r[i] = calc(i);
			vis[i] = 1;
			dfs(dep+1, sum + r[i] * r[i] * PI);
			vis[i] = 0;
		}
	}
}

int main(){
	double ss;
	cin >> n;
	cin >> x1 >> y1 >> x2 >> y2;
	ss = abs(x1 - x2) * abs(y1 - y2);
	//cout << ss << endl;
	for(int i = 1; i <= n; i++)
		cin >> a[i].x >> a[i].y;
	dfs(1, 0);
	cout << int(ss - ans + 0.5) << endl;
	return 0;
}