#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
//#define int ll
//#define endl "\n"
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> ostream & operator<<(ostream & os, vector<T> const &);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }
template<class T, class U> ostream & operator<<(ostream & os, pair<T,U> const & p){ return os << "(" << p.first << ", " << p.second << ") "; }
template<class T> ostream & operator<<(ostream & os, vector<T> const & v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
template<class T> inline bool chmax(T & x, T const & y){ return x<y ? x=y,true : false; }
template<class T> inline bool chmin(T & x, T const & y){ return x>y ? x=y,true : false; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif
// ll const mod = 1000000007;
// ll const inf = 1LL<<60;

typedef long double Real;
#define EPS (1e-10)
#define EQ(a,b) (abs(a-b) < EPS)
#define LE(a,b) (EQ(a,b) || a < b)
#define GE(a,b) (EQ(a,b) || b < a)

#define CR const &

struct Point {
    Real x, y;
    explicit Point (Real x_ = 0, Real y_ = 0);
    explicit Point (Real x_);
    Point operator + (Point CR p) const;
    Point operator - (Point CR p) const;
    Point operator * (Point CR p) const;
    Point operator / (Point CR p) const;
    Point operator * (Real k) const;
    Point operator / (Real k) const;
    bool operator < (Point CR p) const;
    bool operator == (Point CR p) const;
};
Real dot(Point CR p, Point CR q) { return p.x * q.x + p.y * q.y; }
Real cross(Point CR p, Point CR q) { return p.x * q.y - p.y * q.x; }
Real norm(Point CR p){ return dot(p,p); }
Real abs(Point CR p){ return sqrt(norm(p)); }
Point inv(Point CR p){ return Point(p.x,-p.y) / abs(p); }
Real arg(Point CR p){ return atan2(p.y,p.x); }
ostream & operator << (ostream & os, Point CR p){ return os << "(" << p.x << "," << p.y << ")"; }
Point::Point (Real x_, Real y_) : x(x_), y(y_) {}
Point::Point (Real x_) : x(x_), y(0) {}
Point Point::operator + (Point CR p) const { return Point(x + p.x, y + p.y); }
Point Point::operator - (Point CR p) const { return Point(x - p.x, y - p.y); }
Point Point::operator * (Point CR p) const { return Point(x*p.x - y*p.y, x*p.y + y*p.x); }
Point Point::operator / (Point CR p) const { return Point(*this) * inv(p); }
Point Point::operator * (Real k) const { return Point(x * k, y * k); }
Point Point::operator / (Real k) const { return Point(x / k, y / k); }
bool Point::operator < (Point CR p) const { return std::abs(x - p.x) < EPS ? x < p.x : y < p.y; }
bool Point::operator == (Point CR p) const { return EQ(*this,p); }
bool comp_x(Point CR p, Point CR q){ return !EQ(p.x,q.x) ? p.x < q.x : p.y < q.y; }
bool comp_y(Point CR p, Point CR q){ return !EQ(p.y,q.y) ? p.y < q.y : p.x < q.x; }
struct Segment {
    Segment(Point a = Point(), Point b = Point()){ p[0] = a, p[1] = b; }
    Point p[2];
    Point & operator [] (int k) { return p[k]; }
    const Point & operator [] (int k) const { return p[k]; }
};

struct Line {
    Line(Point a = Point(), Point b = Point()){ p[0] = a, p[1] = b; }
    Point p[2];
    Point & operator [] (int k) { return p[k]; }
    const Point & operator [] (int k) const { return p[k]; }
};

struct Circle {
    Point p; Real r;
};

typedef vector<Point> Polygon;

enum {
    CCW = +1,
    CW = -1,
    BACK = +2,
    FRONT = -2,
    ON = 0
};
int ccw(Point CR p0, Point CR p1, Point CR p2){
    Point a = p1 - p0;
    Point b = p2 - p0;
    if(cross(a,b) > EPS) return CCW;
    if(cross(a,b) < -EPS) return CW;
    if(dot(a,b) < -EPS) return BACK;
    if(norm(a) < norm(b)) return FRONT;
    return ON;
}

Polygon andrewScan(Polygon ps){
    // 同一直線上に3点以上存在する場合に
    // ==CW  -> それらを全て含める
    // !=CCW -> 両端以外の点を除く
    int N = ps.size(), k = 0;
    sort(all(ps),comp_x);
    Polygon res(N*2);
    for(int i=0; i<N; i++) {
        while(k>=2 && ccw(res[k-2], res[k-1], ps[i])==CW) k--;
        // while(k>=2 && ccw(res[k-2], res[k-1], ps[i])!=CCW) k--;
        res[k++] = ps[i];
    }
    int t = k+1;
    for(int i=N-2; i>=0; i--) {
        while(k>=t && ccw(res[k-2], res[k-1], ps[i])==CW) k--;
        // while(k>=t && ccw(res[k-2], res[k-1], ps[i])!=CCW) k--;
        res[k++] = ps[i];
    }
    res.resize(k-1);
    return res;
}

bool intersectLL(const Line &l, const Line &m) {
    return abs(cross(l[1]-l[0], m[1]-m[0])) > EPS || // non-parallel
                                                                 abs(cross(l[1]-l[0], m[0]-l[0])) < EPS;   // same line
}
bool intersectLS(const Line &l, const Line &s) {
    return cross(l[1]-l[0], s[0]-l[0])*       // s[0] is left of l
        cross(l[1]-l[0], s[1]-l[0]) < EPS; // s[1] is right of l
}
bool intersectLP(const Line &l, const Point &p) {
    return abs(cross(l[1]-p, l[0]-p)) < EPS;
}
bool intersectSS(const Line &s, const Line &t) {
    return ccw(s[0],s[1],t[0])*ccw(s[0],s[1],t[1]) <= 0 &&
        ccw(t[0],t[1],s[0])*ccw(t[0],t[1],s[1]) <= 0;
}
bool intersectSP(const Line &s, const Point &p) {
    return abs(s[0]-p)+abs(s[1]-p)-abs(s[1]-s[0]) < EPS; // triangle inequality
}

Point projection(const Line &l, const Point &p) {
    double t = dot(p-l[0], l[0]-l[1]) / norm(l[0]-l[1]);
    return l[0] + (l[0]-l[1])*t;
}
Point reflection(const Line &l, const Point &p) {
    return p + (projection(l, p) - p) * 2;
}
double distanceLP(const Line &l, const Point &p) {
    return abs(p - projection(l, p));
}
double distanceLLine(const Line &l, const Line &m) {
    return intersectLL(l, m) ? 0 : distanceLP(l, m[0]);
}
double distanceLS(const Line &l, const Line &s) {
    if (intersectLS(l, s)) return 0;
    return min(distanceLP(l, s[0]), distanceLP(l, s[1]));
}
double distanceSP(const Line &s, const Point &p) {
    const Point r = projection(s, p);
    if (intersectSP(s, r)) return abs(r - p);
    return min(abs(s[0] - p), abs(s[1] - p));
}
double distanceSS(const Line &s, const Line &t) {
    if (intersectSS(s, t)) return 0;
    return min(min(distanceSP(s, t[0]), distanceSP(s, t[1])),
               min(distanceSP(t, s[0]), distanceSP(t, s[1])));
}
Point crosspoint(const Line &l, const Line &m) {
    double A = cross(l[1] - l[0], m[1] - m[0]);
    double B = cross(l[1] - l[0], l[1] - m[0]);
    if (abs(A) < EPS && abs(B) < EPS) return m[0]; // same line
    if (abs(A) < EPS) assert(false); // !!!PRECONDITION NOT SATISFIED!!!
    return m[0] + (m[1] - m[0]) * B / A;
}

pair<Polygon,Polygon> convexCut(Polygon const & g, Line const & l) {
    Polygon right, left;
    int n = g.size();
    rep(i,n){
        Point p1 = g[i], p2 = g[(i+1)%n];
        int c1 = ccw(l[0],l[1],p1), c2 = ccw(l[0],l[1],p2);
        if(c1!=CW) right.push_back(p1);
        if(c1!=CCW) left.push_back(p1);
        if(c1*c2 < 0){
            Point cp = crosspoint(Line(p1,p2),l);
            right.push_back(cp);
            left.push_back(cp);
        }
    }
    return make_pair(left,right);
}

Real area(Polygon const & g){
    Real s = 0;
    int n = g.size();
    rep(i,n) s += cross(g[i], g[(i+1)%n]);
    return abs(s/2);
}

Real solve(Polygon const & g, Real s){
    Real y0 = 0, y1 = 100000;
    rep(i,200){
        Real m = (y0+y1)/2;
        Point a(1,m), b(0,m);
        Real s_ = area(convexCut(g,Line(a,b)).second);
        if(s_+EPS > s) y1 = m; else y0 = m;
    }
    return y0;
}

int main(){
    int n,d,v;
    while(cin >> n >> d >> v && n){
        Real s = (Real)v/d;
        Polygon g(n);
        rep(i,n){
            int x,y;
            cin >> x >> y;
            g[i] = Point(x,y);
        }
        Real ans = 0;
        rep(i,n){
            for(int j=n-1;j>=0;j--) g[j] = g[j] - g[0];
            Point dir = (g[1]-g[0]) / abs(g[1]-g[0]);
            rep(j,n) g[j] = g[j]/dir;
            Real t = solve(g,s);
            ans = max(ans, t);
            rotate(g.begin(), g.begin()+1, g.end());
        }
        printf("%.10lf\n", double(ans));
    }
}

Measured memory_bytes: 1220