#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <ctime>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <set>
#include <map>
#include <iostream>
#include <deque>
#include <complex>
#include <string>
#include <iomanip>
#include <sstream>
#include <bitset>
#include <valarray>
#include <unordered_map>
#include <iterator>
#include <assert.h>
using namespace std;
typedef long long int ll;
typedef unsigned int uint;
typedef unsigned char uchar;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;

#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define REPS(i,x) for(int i=1;i<=(int)(x);i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RREPS(i,x) for(int i=((int)(x));i>0;i--)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();i++)
#define RFOR(i,c) for(__typeof((c).rbegin())i=(c).rbegin();i!=(c).rend();i++)
#define ALL(container) (container).begin(), (container).end()
#define RALL(container) (container).rbegin(), (container).rend()
#define SZ(container) ((int)container.size())
#define mp(a,b) make_pair(a, b)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T> ostream& operator<<(ostream &os, const vector<T> &t) {
os<<"["; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"]"; return os;
}
template<class T> ostream& operator<<(ostream &os, const set<T> &t) {
os<<"{"; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"}"; return os;
}
template<class S, class T> ostream& operator<<(ostream &os, const pair<S,T> &t) { return os<<"("<<t.first<<","<<t.second<<")";}
template<class S, class T> pair<S,T> operator+(const pair<S,T> &s, const pair<S,T> &t){ return pair<S,T>(s.first+t.first, s.second+t.second);}
template<class S, class T> pair<S,T> operator-(const pair<S,T> &s, const pair<S,T> &t){ return pair<S,T>(s.first-t.first, s.second-t.second);}

namespace geom{
#define X real()
#define Y imag()
#define at(i) ((*this)[i])
#define SELF (*this)
	enum {TRUE = 1, FALSE = 0, BORDER = -1};
	typedef int BOOL;
	typedef long double R;
	const R INF = 1e8;
	R EPS = 1e-15;
	const R PI = 3.1415926535897932384626;
	inline int sig(const R &x) { return (abs(x) < EPS ? 0 : x > 0 ? 1 : -1); }
	inline BOOL less(const R &x, const R &y) {return sig(x-y) ? x < y : BORDER;}
	typedef complex<R> P;
	inline R norm(const P &p){return p.X*p.X+p.Y*p.Y;}
	inline R inp(const P& a, const P& b){return (conj(a)*b).X;}
	inline R outp(const P& a, const P& b){return (conj(a)*b).Y;}
	inline P unit(const P& p){return p/abs(p);}
	inline P proj(const P &s, const P &t){return t*inp(s, t)/norm(t);}
	inline int ccw(const P &s, const P &t, const P &p, int adv=0){
		int res = sig(outp(t-s, p-s));
		if(res || !adv) return res;
		if(sig(inp(t-s, p-s)) < 0) return -2;	// p-s-t
		if(sig(inp(s-t, p-t)) < 0) return 2;	// s-t-p
		return 0;								// s-p-t
	}
	
	
	struct L : public vector<P>{	// line
		L(const P &p1, const P &p2){this->push_back(p1);this->push_back(p2);}
		L(){}
		P dir()const {return at(1) - at(0);}
		BOOL online(const P &p)const {return !sig(outp(p-at(0), dir()));}
	};
	struct S : public L{	// segment
		S(const P &p1, const P &p2):L(p1, p2){}
		S(){}
		BOOL online(const P &p)const {
			if(!sig(norm(p - at(0))) || !sig(norm(p - at(1)))) return BORDER;
			// 座標の二乗とEPSの差が大きすぎないように注意
			return !sig(outp(p-at(0), dir())) && inp(p-at(0), dir()) > EPS && inp(p-at(1), -dir()) > -EPS;
			//return !sig(abs(at(0)-p) + abs(at(1) - p) - abs(at(0) - at(1)));
		}
	};
	P crosspoint(const L &l, const L &m);
	struct G : public vector<P>{
		G(size_type size=0):vector(size){}
		S edge(int i)const {return S(at(i), at(i+1 == size() ? 0 : i+1));}
		BOOL contains(const P &p)const {
			R sum = .0;
			REP(i, size()){
				if(S(at(i), at((i+1)%size())).online(p)) return BORDER;	// online
				sum += arg((at(i) - p) / (at((i+1)%size()) - p));
			}
			return !!sig(sum);
		}
		R area()const {
			R sum = 0;
			REP(i, size()) sum += outp(at(i), at((i+1)%size()));
			return abs(sum / 2.);
		}
	};

	inline P proj(const P &s, const L &t){return t[0] + proj(s-t[0], t[1]-t[0]);}
	inline P reflect(const P &s, const L &t){return (R)2.*proj(s, t) - s;}
	inline S reflect(const S &s, const L &t){return S(reflect(s[0], t), reflect(s[1], t));}
	BOOL intersect(const S &s, const S &t){
		const int p = ccw(t[0], t[1], s[0], 1) * ccw(t[0], t[1], s[1], 1);
		const int q = ccw(s[0], s[1], t[0], 1) * ccw(s[0], s[1], t[1], 1);
		return (p>0||q>0) ? FALSE : (!p||!q) ? BORDER : TRUE;
	}
	BOOL intersect(const S &s, const L &l){
		if(l.online(s[0]) || l.online(s[1])) return BORDER;
		return (sig(outp(l.dir(), s[0]-l[0])) * sig(outp(l.dir(), s[1]-l[0])) <= 0);
	}
	inline P crosspoint(const L &l, const L &m){
		R A = outp(l.dir(), m.dir()), B = outp(l.dir(), l[1] - m[0]);
		if(!sig(abs(A)) && !sig(abs(B))) return m[0]; // same line
		if(abs(A) < EPS) assert(false); // !!!PRECONDITION NOT SATISFIED!!!
		return m[0] + B / A * (m[1] - m[0]);
	}
	struct DualGraph{
		struct DEdge{
			int u, v, f, l;
			R a;
			DEdge(int u, int v, R a):u(u),v(v),f(0),l(0){
				while(PI < a) a -= 2*PI;
				while(a < -PI) a += 2*PI;
				this->a = a;
			}
			bool operator==(const DEdge &opp) const{
				return v==opp.v;
			}
			bool operator<(const DEdge &opp) const{
				return a>opp.a;
			}
			bool operator<(const R &opp) const{
				return a>opp;
			}
			friend ostream& operator<<(ostream &os, const DEdge &t) { return os<<"("<<t.u<<","<<t.v<<","<<t.a*180/PI<<")";}
		};
		
		int n;
		vector<P> p;
		vector<vector<DEdge>> g;
		DualGraph(const vector<P> &p):p(p),g(p.size()),n(p.size()){}
		void add_edge(const int s, const int t){
			R a = arg(p[t]-p[s]);
			g[s].emplace_back(s, t, a);
			g[t].emplace_back(t, s, a > 0 ? a-PI : a+PI);
		}
		vector<G> poly;
		
		void add_polygon(int s, int t, R a){
			auto e = lower_bound(ALL(g[s]), a-EPS);
			if(e == g[s].end()) e = g[s].begin();
			if(e->f) return;
			e->f = 1;
			e->l = t;
			poly[t].push_back(p[s]);
			add_polygon(e->v, t, e->a > 0 ? e->a-PI : e->a+PI);
		}
		
		vector<G>& dual(){
			REP(i, n){
				sort(ALL(g[i]));
				UNIQUE(g[i]);
			}
			int s = min_element(ALL(p)) - p.begin();
			poly.emplace_back();
			add_polygon(s, poly.size()-1, -PI*(R).5);
			REP(i, n)REP(j, g[i].size())if(!g[i][j].f){
				poly.emplace_back();
				add_polygon(i, poly.size()-1, g[i][j].a+2.*EPS);
			}
			return poly;
		}
	};
	template<class Func> R simpson(R s, R t, Func func){
		return (t-s)/6*(func(s+2*EPS) + func(t-2*EPS) + 4*func((s+t)*(R).5));
	}

#undef SELF
#undef at
}

using namespace geom;

int f = 0;
namespace std{
	bool operator<(const P &a, const P &b){return sig(a.X-b.X) ? a.X < b.X : a.Y+EPS < b.Y;}
	bool operator==(const P &a, const P &b){return abs(a-b) < EPS;}
	istream& operator>>(istream &is, P &p){R x,y;is>>x>>y;p=P(x, y);return is;}
	istream& operator>>(istream &is, L &l){l.resize(2);return is >> l[0] >> l[1];}
}

int n;
G g;
R minarea(R x, int f = 0){
	vector<P> p = g;
	L xl(P(x, 0), P(x, 1));
	vector<pair<P, int>> ip;
	vector<pii> segs;
	REP(i, n){
		const S &s = g.edge(i);
		if(sig(s.dir().X) && intersect(s, xl)){
			P cp = crosspoint(s, xl);
			if(!sig(norm(cp-s[0]))) ip.emplace_back(s[0], i);
			else if(!sig(norm(cp-s[1]))) ip.emplace_back(s[1], (i+1)%n);
			else{
				segs.emplace_back(i, p.size());
				segs.emplace_back(p.size(), (i+1)%n);
				ip.emplace_back(cp, p.size());
				p.push_back(cp);
				continue;
			}
		}
		segs.emplace_back(i, (i+1)%n);
	}
	sort(ALL(ip));
	REP(i, (int)ip.size()-1){
		if(ip[i].second != ip[i+1].second && g.contains((ip[i].first + ip[i+1].first) * (R).5))
			segs.emplace_back(ip[i].second, ip[i+1].second);
	}
	DualGraph dg(p);
	FOR(it, segs) dg.add_edge(it->first, it->second);
	const vector<G> &poly = dg.dual();
	R ans = .0;
	REPS(i, (int)poly.size()-1) ans = max(ans, poly[i].area());
	return ans;
}

int main(int argc, char *argv[]){
	ios::sync_with_stdio(false);
	while(cin >> n, n){
		P v;
		g.resize(n);
		cin >> v; v = unit(v);
		vector<R> x;
		REP(i, n){
			cin >> g[i];
			g[i] *= P(0, 1) / v;
			x.push_back(g[i].X);
		}
		sort(ALL(x)); UNIQUE(x);
		R ans = INF, ansx = .0;
		REP(i, (int)x.size() - 1){
			ans = min(ans, minarea(x[i]));
			if(minarea(x[i]) < minarea(x[i]+1e-5) || minarea(x[i+1]) < minarea(x[i+1]-1e-5)) continue;
			R l = x[i], r = x[i+1];
			while(r-l > 1e-6){
				R ml = minarea((2*l+r)/3);
				R mr = minarea((l+2*r)/3);
				ans = min(ans, ml);
				ans = min(ans, mr);
				if(ml < mr) r = (l+2*r)/3;
				else l = (2*l+r)/3;
			}
		}
		printf("%.10f\n", (double)ans);
	}
	return 0;
}

Measured memory_bytes: 1420